342.for good (=for ever)永远地，长期地
343.take……for granted (=assume to be true)把……认为理所当然的
344.be grateful to sb. for sth.因……感谢某人
345.on the ground(s) of (=because of) 由于……
346.fall to the ground(计划，希望等)失败，落空
347.on one‘s guard (against) 谨防，警惕 (be)on guard站岗
348.guard against (=defend，keep safe) 警惕，防止guard……against警卫……防止
349.guess at猜，估计
350.by guess靠猜
