It is important and necessary that one ____ a foreign language so that he can be better equipped for hisfuture.[ ]

we will build the dam has not beendecided yet, ______

下列各组句子中，加横线词的意义和用法相同的一组是（ ）

I will come to attend your lecture at 10:00 tomorrow— I’m sorry, by then my lecture will have ended and I＿＿my guests in my office

Last month, the Japanese government expressed their thanks for the air they_______ from China