— Sorry. I returned it to the library just now. Maybe it is still ____.

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Can you imagine astronauts' everyday life in space? They also need to eat,  1 , exercise and relax. They do the same things as us, but they do2 differently.

    On Earth, we put food on a plate and water in a glass. Gravity(重力) holds the food down and keeps the water in the glass.  3 there is almost no gravity in space, so food can float(漂浮) away, and astronauts must eat and drink4  .

    Sleeping is very different in space. Some astronauts like to float in the air, but most like to be in a 5bag. They tie the bag to a wall 6 they won't float away at night. Exercise is very important in space. On Earth, your legs 7 your body, but in space, astronauts float. So they do not use their legs often. This is very  8their legs, so they must exercise for thirty minutes every day.

    After a day's work, astronauts relax. They may listen to music, read, watch films, play games, or talk to their friends and families  9  the radio. Sometimes they just enjoy 10 in the air.

汤姆惊奇地发现：欧洲地名与其他地区地名非常相似，如大洋洲有新西兰（NewZealand），荷兰有西兰省（Zealand）；美国有新奥尔良（New Orleans），法国有奥尔良（Orleans）。对此，你对两者之间关系的合理解释是

将一矩形纸片OABC放在平面直角坐标系中，O（0，0），A（6，0），C（0，3）．动点Q从点O出发以每秒1个单位长的速度沿OC向终点C运动，运动 $\frac{2}{3}$ 秒时，动点P从点A出发以相等的速度沿AO向终点O运动．当其中一点到达终点时，另一点也停止运动．设点P的运动时间为t（秒）．