1)我们不知道或没有必要说明动作的执行者是谁的时候(这时不带by引起的短语)。 Printing was introducedsintosEurope from China. Look! There is nothing here. Everything has been taken away. 2)当我们强调或兴...
1)带情态动词的被动结构。其形式为:情态动词+be+过去分词。 【例如】 The baby should be taken good care of by the baby-sitter. This instrument must be handled with great care. In this sense, bad thing...