选出能够替换句中划线部分的选项。

a. trouble   b. quite worried   c. very important   d. running after    e. waste things

( ) 1. The dog likes chasing the chick.

( ) 2. It’s crucial that we study English well.

(     ) 3. She’s anxious because of the test.

(     ) 4. Xiao Ning found garbage in front of the house.

(     ) 5. Don’t bother your father. He is busy with his work now.

扩散通风可用于无瓦斯涌出、入口宽度大于1.5m、长度不超过（）m的硐室。

A、10

B、8

C、6

D、5