词汇选项
Among other things they had to stand pressure three times the force of gravity and carry out both physical and mental tasks while exhausted from strenuous physical exercise. ________. During that time they suffered backaches and other discomforts. When they were finally allowed up， the more physically active women were especially subject to pains due to a slight calcium loss.
A.They need less food and less oxygen and they stand up to radiation better.
B.At the end of ten days， they had to spend a further twenty days absolutely confined to bed.
C.Men's advantages are virtually wiped out by the zero-gravity condition in space.
D.Results of the tests suggest that women will have significant advantages over men in space.
【正确答案】B
【答案解析】这一段是客观地描述已进行过实验的情况，所以动词用的都是过去时。
