【题目】______ trees have been planted in our town since 2013.

【题目】 I listened to Professor Chen-Ning Franklin Yang’s lecture about his study and physics, but I failed to get its key ______ .

【题目】Why not ____ your teacher for help when you can't finish _____ the story by yourself?

【题目】Look! There is a chair ________ three legs in the meeting room.

【题目】---Whose trousers are these? Are they ______? ---No， they are _____.

【题目】- do you prepare for an exam?

【题目】-Could you give me some advice on learning English?

【题目】 -Many students don't know how to____ stress and become worried.

【题目】Perhaps the famous football star won’t play________football any longer．

【题目】 — Hi, Jack. What’s that on the desk?