教师在对教具和实验进行演示操作的同时，最重要的是必须（ ）。

(单选题)—It’s too warm in the room.—You’d better ______ your coat. (单选题)Success comes to those who are willing to risk making mistak (单选题)—What’s the matter with John? He has been sitting there for (单选题)Up to now, the Hope Project ______ thousands of children who (单选题)With the fight against piracy ______, more and more people f (单选题)Can you make a sentence to ______ the meaning of the phrase? (单选题)—If you ______ away our secret that day, the current situati (单选题)My grandparents are ______. (单选题)—Sally, where are you? ______ friends are here.—I’m at the s (单选题)The boy is good ______ making kites ______ silk.