制氧机中主冷乙炔含量达（）ppm，应停机处理。

A、0.1ppm

B、1ppm

C、1.5ppm

用所给词的适当形式填空。

1．________ your sister ________(like) cold weather?

2．Jim can ________ in the river. He often ________. He likes ________ a lot. (swim)

3．Maria ________(not do) housework last Sunday.

4．It's a beautiful ________(sun) day. Let's ________(go) to the park.

5．My uncle ________ many things. He likes ________ things. Now, he ________ a new machine. (make)

6．John wants ________(ride) the machine like a bike.

7．Thank you very much for ________(teach) us so well.

8．Mr. and Mrs. Brown have two ________(child).

9．How many ________(play) are there on the playground?

10．Mr. Wu often goes ________(fish) at East Lake.