题目内容：
根据以下内容，回答题。It was wonderful up there. Ralph wanted to reach out and 21 a star, for they 22 so close. He could see the earth getting smaller and smaller.
The ship circled around a made star called Mars(火星) , and his space friends 23 Ralph understand that this was their home.
He wanted to ask all kinds of 24 , but no one could answer him. There was nothing to eat or drink. There people had only 25 colours pills which they can eat 26 they were hungry.
Soon it became 27 harder for Ralph to breathe than he felt at first. He felt 28 light that he could not even stand 29 his own feet. "If I could only have some water," he 30 , "and a ride back down to the earth!"
The spacemen knew that it was 31 for Ralph to leave. He could not live up there 32 longer without special air or suit like theirs. So they took him to a part of the ship where there was 33 enough for just one man. A door closed over his head and 34 a minute Ralph was flying down to the earth in his own rocket ship.
Suddenly he felt the rocket 35 down and then stopped. He was back on the earth.
（ ） A．get
B．touch
C．hit
D．knock
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答案解析：