问题

One way for students to prevent H7N9 flu virus is to openthe windows of the classroom to allow the air to ________

A:haddecreased
B:decreased
C:has been decreasing
D:isdecreasing

正确答案是：

同类题型

Where is your new home now? — In the new developed zoneBut I _____ downtown for five years[ ]

Many students listened to the lecture, but I wondered how much work they took________.[ ]

I often hear the girl_______ beautifully next door. When I passed the door, I heard her _______ just now.

She’s already left for Nanjing, — Yes, she is in Nanjing now.

Do you think _______ computer games ______ much time