The challenge we face is to find ways to meet the needs of our growing
population while _______(protect) the environment.这里填protecting是省略了主语和be动词吗?但是主语不是the challenge吗?
...nt to be First lady since Louisa.她是自路易莎成为第一夫人以来的第一位移民。2)She is America's only First Lady to speak five languages.她是美国唯一会讲五种语言的第一夫人。上述2句都使用了不定式,请教老师:a) 句1)使用不定式,不定式和...