题目内容
用正确的动词时态填空。
How long the children ________(play)computer games?
The aliens say they come from Zeton and ________(travel)for 2 years．
How many times you ________(swim)in the sea?
They _______(visit)this national park twice this month．
－Will someone go and get Dr．White?
－He ________ already ________(send)for．
