Since his blood pressure is much higher than it should be, his doctor insists upon it that he give up smoking. 他的血压太高了，医生坚持要他戒烟。
如何分析上句中的 upon it that?
我们已多次提到，介词是不能直接跟 that 从句连用的。如果带介词的动词需要使用 that 从句作宾语，那该怎么办呢？办法很简单：在 that 从句前加个 it，让它充当形式宾语，就行了。see to it that 便属于此种句型。（见 see to it that/see that）。再看下面的实例：
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You may depend upon it that the data are correct. 你可以相信这些数据是正确的。
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The operators will answer for it that the test will be reliable. 操作人员担保这个试验将是可靠的。
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They are all counting on it that the trial-manufacture will be a success. 他们都指望试制取得成功。
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Measuring electromotive force with a voltmeter, we should see to it that the voltmeter is placed in parallel with the electric source. 用伏特计测量电动势时，务必使伏特计与电源并联。
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Look to it that there are no loopholes in this contract. 要注意使这份合同没有漏洞。①it/its
（A）She got a sense of it being her duty to do something. 她意识到她有义务做点事儿。（《大学英语语法》，p.237）
(B) He had no doubt of its being highly agreeable to her. 他对它很适合她的口胃深信不疑。(《高级英语语法》，高等教育出版社，p.440)
《高级英语语法》的作者们解释说：“动名词复合结构多用所有格 its。”英语的实际使用情况确实如此吗？
用代词的所有格(物主代词)充当动名词的逻辑主语和用代词的宾格充当动名词的逻辑主语,这在英语里都是可以见到的。到底哪种形式用得普遍呢?关于这一点,R.Quirk等与上述作者持有完全相反的观点,他们说:
"The genitive is also rare with a pronoun with nonpersonal reference. (当代词不是指人时, 使用所有格形式是很罕见的):
I look forward to getting warmer in spring. ”(CGEL,1194) 我盼望着春天天气变暖。