1A thermos is used ( ) keeping hot.AofBinCoffDdown 2They had learn one thousand English words...

题目

1A thermos is used ( ) keeping hot.AofBinCoffDdown 2They had learn one thousand English words...
1A thermos is used ( ) keeping hot.AofBinCoffDdown 2They had learn one thousand English words ( ) the end of last term.AatBinCbyDon第1题选择并说明理由；第2题选C,为什么不选A,两者的区别?
第一题答案是C，是它有误吗？

答案

1.选C.但是Off（介词）不是跟used搭配的.
你可以查询off的意思.就是热水瓶是用来隔开（外界的温度）进行保温.
2.C by是表示到上个学期末为止（一段时间）.at只是表示在期末时（一个点不表一段时间）.