题目

使用显微镜的正确步骤是①对光，直到整个视野呈白色②调节粗、细准焦螺旋，以便看清物像③放置玻片标本，并用压片夹压住④取镜、安放⑤收镜并放回原处A.④①③②⑤      B.⑤③①②④       C.④①②③⑤        D.①②③④⑤  答案：A解析:显微镜的使用步骤：（1）取镜和安放；（2）对光；（3）观察；（4）收镜。 28. Think after you read ____.A．which words do you need to look upB．you need to look up which wordsC．which words need you look upD．which words you need to look up