【正文】 ge three ti m es on our journey and that the fi rst change woul d be the m ost powerful . Then we were off. As the rocket rose i nto the ai r, we were pushed back i nto our seats because we were tryi ng to escape the pul of the earth’s gravi ty. It was so hard that we coul d not say anythi ng to each other. Gradual y the wei ght l essened and I was abl e to tal k to hi m. “ Why i s the spaceshi p not fal i ng back to the earth? O n the earth i f I fal l from a tree I wil l fal l to ground. ” I asked. “ We are too far from the earth now to feel i ts pul, “ he expl ai ned, “ so we feel as i f there is no gravi ty at al. When we get cl oser to the m oon, we shal feel its gravity pul i ng us, but i t wi l not be as strong a pul l as the earth’s. “ I cheered up imm edi atel y and fl oated wei ghtl esl y around i n our spaceshi p cabi n watchi ng the earth be e sm al l er and the m oon l arger. When we got there, I wanted to expl ore i mm edi atel y. “ Com e on, ” I sai d. “ If you are ri ght, m y m as wi l be l ess than on the earth because the m oon is sm al l er and I wi l be abl e to m ove m ore freel y. I mi ght even grow tal er i f I stay here l ong enough. I shal certai nl y weigh l ess!” I l aughed and cli mbed down the steps from the spaceshi p. But when I tri ed to step forward, I found I was carri ed twi ce as far as on the earth and fel l over. “ O h dear, ” I cri ed, “ wal ki ng does need a bi t of practi ce now that gravi ty has changed. ” After a whil e I got the hang of i t and we began to enjoy oursel ves. Leavi ng the m oon’s gravi ty was not as pai nful as l eavi ng the earth’s. But returni ng to the earth was very fri ghteni ng. We watched, amazed as fi re broke out on the outsi de of the spaceship as the earth’s gravi ty increased. Agai n we were pushed back hard i nto our seats as we cam e back to l and. “ That was very exhausti ng but very exciti ng too, ” I sai d. “N ow I know m uch m ore about gravi ty! Do you thi nk we coul d bisi t som e stars next tim e?” “O f course,” he sm il ed, “ whi ch star woul d you l i ke to go to?” Caught by a bl ack hol e The spaceship warned Li Yanpi ng and m e to be ready as we were approachi ng the “black hol e”. We coul d see som e fai nt l i ghts around what l ooked li ke an em pty space. Li Yanpi ng sai d, “ That em pty hol e i s l i ke a m outh al ways needi ng to be fed. Those l i ghts are thi ns that are being pul ed i nto tim e by the gravity of the hol e.” We watched with i nterest and am azem ent at the li ghts whi ch seem ed to be goi ng fai nter and fai nter round the edge of the bl ack hol e. Just then the li ghts on our spaceshi p went our the and the puter stopped working. What was happeni ng? I tri ed to turn the spaceshi p away from the hol e but i t woul d not m ove. Woul d i t eat us too? Suddenl y the spaceshi p jum ped and began to m ove round the edge of trhe hol e too. The gravi ty of the “black hol e” was pul li ng us i nto i ts “m outh”. As the spaceshi p m oved round the bl ack hol e, I fel t rather si ck. My m outh went dry and I cl osed m y eyes. Al l the stori es about what happened when you were caught by the gravi ty of a “bl ack hol e” seem to be true. But then the spaceship jum ped agai n. Thi s tim e i t m oved si deways and away from thi s edge of the “bl ack hol e”. Som eone watchi ng m e woul d have seen the spaceshi p flyi ng li ke a bi rd away from the “bl ack hol e”. But we fel t nothi ng. At l ast we were abl e to l ook around us. Luckil y the puter had started worki ng agai n. We real i zed that we had di scovered som ethi ng new about “black hol e”. If you go i nsi de the edge of a “black hol e”, i t wil l “eat” you and there i s no escape。s too bad, ” he sai d. “Montreal i s a ci ty wi th wonderful restaurants and cl ubs. Most of us speak both Engl i sh and French, but the ci ty has French cul ture and tradi ti ons. We l ove good coffee, good bread and good m usi c. ” That ni ght as the transfer was speedi ng al ong a chance to make a tri p i nto space wi th m y friend Li Yanpi ng, an astronom er. We vi si ted the m oon i n our spaceshi p! Before we l eave, Li Yanping expl ai ned to m e that the forece of the gravi ty woul d change three ti m es on our journey and that the fi rst change woul d be the m ost powerful . Then we were off. As the rocket rose i nto the ai r, we were pushed back i nto our seats because we were tryi ng to escape the pul of the earth’s gravi ty. It was so hard that we coul d not say anythi ng to each other. Gradual y the wei ght l essened and I was abl e to tal k to hi m. “ Why i s the spaceshi p not fal i ng back to the earth? O n the earth i f I fal l from a tree I wil l fal l to ground. ” I asked. “ We are too far from the earth now to feel i ts pul, “ he expl ai ned, “ so we feel as i f there is no gravi ty at al. When we get cl oser to the m oon, we shal feel its gravity pul i ng us, but i t wi l not be as strong a pul l as the earth’s. “ I cheered up imm edi atel y and fl oated wei ghtl esl y around i n our spaceshi p cabi n watchi ng the earth be e sm al l er and the m oon l arger. When we got there, I wanted to expl ore i mm edi atel y. “ Com e on, ” I sai d. “ If you are ri ght, m y m as wi l be l ess than on the earth because the m oon is sm al l er and I wi l be abl e to m ove m ore freel y. I mi ght even grow tal er i f I stay here l ong enough. I shal certai nl y weigh l ess!” I l aughed and cli mbed down the steps from the spaceshi p. But when I tri ed to step forward, I found I was carri ed twi ce as far as on the earth and fel l over. “ O h dear, ” I cri ed, “ wal ki ng does need a bi t of practi ce now that gravi ty has changed. ” After a whil e I got the hang of i t and we began to enjoy oursel ves. Leavi ng the m oon’s gravi ty was not as pai nful as l eavi ng the earth’s. But returni ng to the earth was very fri ghteni ng. We watched, amazed as fi re broke ou