【求助】动名词和名词在PREP的总结

什么时候该用动词什么时候该用名词呢，我做PREP的时候有的题目说选动名词更好，但有的题目说的却相反，下面是两道例题。请NN指教

Whereas heat transferred between the ocean and the atmosphere occurs more rapidly when the ocean is warmer than the air, it is slow when the ocean is colder.

(D) Transferring heat between the ocean and the atmosphere occurs slowly when the ocean is colder than the air and more rapidly when it is warmer.

Scientists at the Los Alamos National Laboratory have succeeded for the first time in mining heat from the Earth's interior and producing energy on a commercial scale, enough for efficient generation of electricity and heating factories and homes.

(E) to produce enough energy on a commercial scale for efficient generation of electricity and heat

答案分别为CD，请问除了别的错误，在什么时候该用动名词什么时候该用名词？

发错区了。。

1、Transferring heat不明确是Transferring是动名词还是形容词，如是后者 heat occurs slowly明显错。

2、efficient generation of electricity and heat factories and homes 明显错，d中的for heating factories and homes和 for generating electricity efficiently 并列。

不要太执着于用那种形态，往往是因为形态造成了句子不准确，这才是错误原因。