力量慢慢减小，我才能够同他讲话。我问道："为什么宇宙飞船不会落回到地球呢？在地球上的时候，如果我从树上掉下来，总会朝地上落下去的。"李彦平解释说："现在我们离地球太远了，感觉不到地球的拉力，所以我们感觉好像完全没有地球引力了。当我们更接近月球时，就会感到月球的引力在拉我们。但是月球的引力不像地球的引力那么大。"我立刻感到很高兴，由于失重我在太空舱里飘来飘去，我望着(身后的)地球越来越小，而(前方的)月球越来越大。

　　When we got there, I wanted to explore immediately."Come on\s\up1(23(23)，" I said."If you are right, my weight will be less than on the earth because the moon is smaller and I will be able to move more freely.I might even grow taller if I stay here long enough.I shall certainly weigh less！" I laughed and climbed down the steps from the spaceship.But when I tried to step forward\s\up1(24(24)， I found I was carried twice as far as\s\up1(25(25) on the earth and fell over\s\up1(26(26)."Oh dear，" I cried, "walking does need a bit of practice\s\up1(27(27) now that\s\up1(28(28) gravity has changed." After a while I got the hang of\s\up1(29(29) it and we began to enjoy ourselves\s\up1(30(30).

　　Leaving the moon's gravity was not as painful as leaving the earth's.But returning to the earth was very frightening.We watched, amazed as fire broke out\s\up1(31(31) on the outside of the spaceship as the earth's gravity increased.Again we were pushed hard into our seats as we came back to land."That was very exhausting\s\up1(32(32) but very exciting too，" I said."Now I know\s\up1(33(33) much more about gravity! Do you think we could visit some stars next time？""Of course，" he smiled, "which star would you like to go to？"

　　\s\up1(23(23)come on快点儿。常用于祈使句中以鼓励某人，意为"动手吧；快点儿；加油"。

　　\s\up1(24(24)step forward朝前走；迈步向前

　　\s\up1(25(25)twice as far as"......的两倍远"。倍数表示法：倍数(twice, three times ...)＋as＋adj./adv.原级＋as。

　　\s\up1(26(26)fall over跌倒；摔倒

　　\s\up1(27(27)动名词walking在此处作主语。does为助动词，加强语气，意为"确实"，其后跟动词原形。

　　\s\up1(28(28)now that既然(引导原因状语从句)

　　\s\up1(29(29)get the hang of 熟悉；掌握；理解

\s\up1(30(30)enjoy oneself尽情地玩；玩得高兴