请解释为什么第一个must后面加be 而第二个must后面没有加beShe knows that a secretary must be pleasant and helpful nomatter how busy she is.She knows she must keep calm if a caller gets impatient or becomes angry.
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![请解释为什么第一个must后面加be 而第二个must后面没有加beShe knows that a secretary must be pleasant and helpful nomatter how busy she is.She knows she must keep calm if a caller gets impatient or becomes angry.](/uploads/image/z/13999567-31-7.jpg?t=%E8%AF%B7%E8%A7%A3%E9%87%8A%E4%B8%BA%E4%BB%80%E4%B9%88%E7%AC%AC%E4%B8%80%E4%B8%AAmust%E5%90%8E%E9%9D%A2%E5%8A%A0be+%E8%80%8C%E7%AC%AC%E4%BA%8C%E4%B8%AAmust%E5%90%8E%E9%9D%A2%E6%B2%A1%E6%9C%89%E5%8A%A0beShe+knows+that+a+secretary+must+be+pleasant+and+helpful+nomatter+how+busy+she+is.She+knows+she+must+keep+calm+if+a+caller+gets+impatient+or+becomes+angry.)
请解释为什么第一个must后面加be 而第二个must后面没有加beShe knows that a secretary must be pleasant and helpful nomatter how busy she is.She knows she must keep calm if a caller gets impatient or becomes angry.
请解释为什么第一个must后面加be 而第二个must后面没有加be
She knows that a secretary must be pleasant and helpful no
matter how busy she is.She knows she must keep calm if a caller gets impatient or becomes angry.
请解释为什么第一个must后面加be 而第二个must后面没有加beShe knows that a secretary must be pleasant and helpful nomatter how busy she is.She knows she must keep calm if a caller gets impatient or becomes angry.
must是情态动词,用法等同于强调语气时的一般现在时的do.
must do sth.OR must be + doing/adj.
第一个加be,因为后面接的形容词pleasant,be动词+形容词,表示状态.
第二个不加be,因为后面接的词keep是动词.
must 后面跟动词原形
第一个be后面是形容词
第二个must 后面直接加动原形了
加个be动词化
must+ 动词原形,第一个后无动词,只有be pleasant短语
第二个有动词keep所以不用be
因为pleasant是个形容词,而情态动词后面要跟动词,所以加be,第二个keep就是动词嘛
前面的主语是a secretary ,系表结构
后面是直接跟动词原形
所以前面的must后面加be了
must情态动词 跟动词原型
be是am/is/are的原型,keep就是keep这个词的原型,不需要be啊
第一个用be 是因为后面是形容词,
第二个不用be 是因为后面是动词,
那是因为第一个后面跟的是一个形容词,所以must 后需要加个系动词来构成系表结构
而第二个 直接是情态动词加动词原形构成句子的谓语部分
所以不需要加了
第一个后面要加形容词 pleasant 所以要加系动词BE
第二个后面直接跟实义动词所以没有家BE的必要