谓语动词的形式
谓语动词切忌用“行为动词 + 原形动词”、“be + 原形动词”。
情态动词+原形动词。如:You'd better go over the lesson.(你最好复习这一课。)
shall/ will/ would+原形动词。如:They should have been there once.(他们应该去过那儿。)
be+现在分词或者过去分词。如:What are you doing this evening?(今晚你打算做什么?)/ Many trees have been cut down since 1970s.(自从20世纪70年代大批树木被砍伐。)