I failed again. I wish I ____ harder.—But you ____.

The number of people present at the meeting_________about 1000 , a large number of whom _______ experts from abroad.

he ______word “ PM2.5” constantly appearing in _____media reports, people pay greater attention to it and seek health tips for smoggy days.

I have bought two pens, ____ write well.

给下面语句排序，衔接恰当的一项是（ ）①刘继庄《广阳杂记》云：“驴鸣似哭，马嘶如笑。”②幽默当然用笑来发泄，但是笑未必就表示着幽默。③自从幽默文学提倡以来，卖笑变成了文人的职业。④而马并不以幽默名家，大约因为脸太长的缘故。⑤老实说，一大部分人的笑，也只等于马鸣萧萧，充不得什么幽默。