—Would you like to go and watch a tennis match this weekend with us?—I'm sorry, but I've got ________ plans.

(2013·高考浙江卷)A good listener takes part in the conversation，________ ideas and raising questions to keep the talk flowing.

While our city tries impatiently to change its appearance by tearing down old buildings, more and more citizens are suggesting ways to ___________ the historically important architecture

(2013·山东省胶东示范学校二模)—It's dangerous to take photos of lightning.—The challenge is not for ________， but I think it's worth  attempting.

 What a great _____ do you think a word of praise from the teacher will have on pupils?