prevent ... from ...
[观察]阅读下列各句，并观察prevent ... from ...在句中的用法。 1. The bad cold prevented / stopped Alice ( from ) taking part in the sports meet.=The bad cold kept Alice from taking part in the sports meet.
2. The old lady can’t be prevented / stopped /kept from joining the club. [点拨] prevent ... from ... / stop ... from ... / keep ... from ...三者都表示“阻止某人（某物）干某事”,通常可以互换,介词from后常接动词-ing形式。
用于主动语态时，prevent sb. / sth. from doing sth.和stop sb. / sth. from doing sth.中的from常可省略，而keep sb. / sth. from doing sth.中的from不可省略（若省略from，那么keep sb. / sth. doing sth.表示“使某人或某物一直干某事”）。如句1；用于被动语态时，三者中的from都不能省略。如句2。
[小试]用下列单词的适当形式完成下列句子。 preventstopkeep
1. Nothing will ____________ us from coming here.
2. The heavy snow ____________ the children going to school. 3. I’m sorry to have ____________ you waiting for so long. 4. We were ____________ by heavy smog from seeing anything. Key:
1. keep / stop / prevent 3. kept2. prevented / stopped 4. prevented / stopped / kept
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prevent... from
