children brains cannot develop ___they lack prose in
A.since B.when C.because D. unless
选哪个,解释
解答:这里应该用选项D unless。unless的基本含义是if not,表示一种假设的条件。翻译:如果缺乏蛋白质,孩子的大脑就不能正常发育。
拓展:英语中unless只有一种单一词性,即连词。其基本含义是if...not; except if or except when,也就是“如果不;除非;;除非在...的时候”。例如:You will fail in French unless you work harder. 你要是不加把劲儿,法语考试就要不及格了。Come at eight o'clock unless I phone. 我如果不打电话,就请八点钟过来。I sleep with the window open unless it's really cold. 我总是开着窗户睡觉,除非天气非常寒冷。注意:英语中unless与if...not... 的用法是完全一样的。
例句:
① Follow the green signs unless you have good to declare.
② Follow the green signs if you haven't got any good to declare. 未携带申报货物者,请沿绿色标记通行。
③ We would have had a lovely holiday if it hadn't rained every day.
④ We would have had a lovely holiday unless it had rained every day. 要不是每天下雨的话,我们的假期就过得愉快了。