用所给动词的适当形式填空。

1. ____________ (not do) your homework now.

2. They are going to ____________ (play) basketball.

3. It ____________ (not rain) in winter.

4. Can you ____________ (see) some birds in the sky?

5. He ____________ (sit) on the grass now.

6. Last year, we ____________ (fly) to Shanghai for my holiday.

调节胰岛素分泌的最重要因素是

A．胰高血糖素的局部调节作用

B．血糖浓度

C．胃泌素等胃肠激素

D．血中游离脂肪酸

E．下丘脑调节性多肽的作用