1. He is not really sad but putting it on.
2. You should work hard, otherwise you will find it hard to keep up with other classmates.请问，第一句话的put为什么要加ing呢。啊，不好意思，刚刚一忙就糊涂了，不是putting，是puts恩 没事 谢谢你的帮忙 我知道了