underestimate
vt. 对…估计不足, 低估
n. 估计不足, 低估
联想：overestimate 估计过高
1.I underestimate the distance, and am exhausted.
没想到这么远, 我可累坏了。
2.Never underestimate your opponent.
千万不要低估对手。
3.Don't underestimate yourself.You look stupid but you have great intelligence.
别低估你自己，你看起来愚笨，其实很聪明滴。
underground
adj. 地下的； 地下组织的, 秘密的
adv. 在地下
n. 地铁；地下组织或活动
1.There is an underground park here.
这里有一个地下停车场。
2.The spy never told his family about his underground activities.
那个间谍从来不把他的地下活动告诉他的家人。
3.The railway track goes underground for a short distance.
铁轨有一段不长的路程铺设在地下。
4.London has a well-developed underground system.
伦敦的地铁很发达。
5.His father is a member of the underground.
他父亲是一名地下组织的成员。
undo
vt. 松开, 解开；毁灭; 败坏
1.Can you undo this knot?
你能解开这个结吗?
2.He bent down and undid the laces of his shoes.
他弯腰解开鞋带。
3.What is done cannot be undone.
覆水难收。
4.He did wrong, and in the end his wrongs undid him.
行恶者终以其恶毁其身。
up-to-date
adj. 现代的; 最新的
1.He bought an up-to-date textbook.
他买了一本最新的教科书。
2.All my correspondence is up-to-date.
我所有的通信手段都是跟上时代的。
3.I want to buy some up-to-date clothes.
我要去买几件新潮衣服。
