在Windows环境中，菜单项呈灰色，表明该菜单目前（）。
参考答案：不可用（或无法使用、不能使用、无效）
用括号内所给动词的适当形式填空。
1. It _ (be) very windy yesterday. So we had to stay at home.
2. —Did you _ ( go) to the park last week?
—Yes, I _ ( do).
3. His funny joke _ ( make) me laugh yesterday.
4. I am __ (real) sorry. I'm late.
5. He often _ ( play) basketball with his classmates.
多云的自然光是属于（）。
A.硬光
B.散射光
C.强光
D.弱光
