Mr Smith ______ a book about China last year but I don’t know whether he has finished it

9Mike must be angry with me, for he walked____me without even saying hello

下列各句中，没有语病的一句是（ ）

－Sunday is a public holiday, ___ children should get close to nature.－But most of them have several lessons to attend.

When solving the problem a second time, you’d better be more careful____you made a mistake