MALE STUDENT: Exactly! So, yeah, the chinampas... The article said, very clearly, these floating gardens are proof that the Aztecs invented hydroponic farming.
Para14
FEMALE PROFESSOR: Well, chinampas are artificial islands, built up in shallow lakes-islands made from packed earth and weeds, and, uh, material from the bottom of the lake.
Para15
FEMALE PROFESSOR: They may have appeared to be floating in the water, but in fact they reach all the way to the bottom of the lake.
Para16
FEMALE PROFESSOR: So the primary growing medium-what the plants draw nutrients from-is actually soil, not water.
请问老师,这里的they may have appeared to be floating in the water和hey may have appeared to flaot in the water,在语意和逻辑上有什么区别?
to do 表示在appeared 之后发生。
to be doing 表示与appeared 同时发生。
不定式与谓语动词表示的时间关系:
1. 一般式(体):It seems to rain this afternoon.
一般式往往表示其动作在谓语动词之后发生。例句说明,“今天下午看起来要下雨。” rain应在seem 之后发生。
2. 进行式(体):It seems to be raining outside.
进行式往往表示不定式的动作与谓语动词同时发生。例句说明,“外面好像正在下雨。”(指在室内听见外面有下雨的声音或迹象), rain 和seem 同时发生。
3. 完成式(体):It seems to have rained last night.
完成式表示不定式的动作发生在谓语动词之前。例句说明,“昨晚好像下了雨。”(指早晨起床后发现地面潮湿,有下雨的迹象,才做出如此判断), rain 发生在seem 之前。
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