biology
n. 生物学
1.She has a degree in biology.
她具有生物学的学位。
2.He devoted his attention to the study of biology. 他专心致志于研究生物学。
captive
adj. 被俘的, 被捕获的
n. 战俘, 俘虏
搭配：be taken captive 活捉，被俘
同根： capture 俘获，战利品
1.The rock star had a captive audience.
那位摇滚歌星倾倒了许多观众。
2.The captives are wearing chains.
俘虏们带着镣铐。
cash
n. 钱, 现款
vt. 把支票兑换成现金
搭配：to pay in cash 现金支付
to pay by cheque 支票支付
to pay by credit card 信用卡支付
1.You'd better pay in cash.
你最好付现款。
2.Cash on delivery?
货到付款吗？
3. Cash me this , please.
请把这个给我兑换成现金。
census
n. 人口普查, 统计
A census of population is taken every ten years.
人口普查每十年进行一次。
challenge
n. 挑战, 邀请比赛 ;怀疑, 质问 ;艰巨的任务
vt. 挑战 质疑 ;考验
辨析：动词challenge本身已经含有向，对...的意思，所以不要多余再家to.
1.I did not think he was right, so I challenged him.
我认为他是不对的, 因此向他提出质疑。
2.The job doesn't really challenge him.
这项工作不能真正地考验他。
3.Are you going to take the challenge lying down.
你打算屈服于这种挑战吗？
