Prep 1-83 介词的补出

83.

Stock levels for domestic crude oil are far lower than in past years, leaving domestic oil prices vulnerable to any hints of oil supplies being disrupted in the Middle East or to any unexpected consumer demand growth possibly prompted by colder-than-normal temperatures.

(A) leaving domestic oil prices vulnerable to any hints of oil supplies being disrupted in the Middle East or to any unexpected consumer demand growth possibly

(B) leaving domestic oil prices vulnerable to any hints of oil supply disruptions in the Middle East or any unexpected growth in consumer demand that might be

(C) leaving domestic oil prices vulnerable to any hints of oil supplies that are disrupted in the Middle East or to any unexpected growth in consumer demand as was possibly

(D) resulting in the fact that domestic oil prices are vulnerable to any hints of oil supplies being disrupted in the Middle East or to any unexpected consumer demand growth possibly

(E) resulting in the fact of domestic oil prices that are vulnerable to any hints of oil supply disruptions in the Middle East or to any unexpected growth in consumer demand that might be

请问为什么这里B的介词to不用补出而很多情况下平行介词需要补出，到底什么时候需要补出？

例如

121

(A) When the temperature of a gas is increased, it is either accompanied by an increase in pressure if the gas is enclosed in a container, or

(B) When the temperature of a gas is increased, it is accompanied either by an increase in pressure if it is enclosed in a container or

(C) When the temperature of a gas is increased, the increase is either accompanied by an increase in pressure if the gas is enclosed in a container or by

(D) Any increase in the temperature of a gas is either accompanied by an increase in pressure if it is enclosed in a container, or by

(E) Any increase in the temperature of a gas is accompanied either by an increase in pressure if the gas is enclosed in a container or by

顶一下

恩，没考虑过这个问题。根据我做题的经验是介词都是要补出的，但是to是可以省略的。

原来是这样的啊，好吧，谢啦~