People should open the window in the morning to make air __________ in order to keep the indoor air fresh.[ ]

_____ and I’ll get the work finished. 　　[ ]

Mrs. Green takes the _______that children should be allowed to learn at their own speed.

Li Jun will have a math test tomorrow. As he isn’tgood at math, he is ______.

________ to the hot weather here was more difficult than I had expected.