Henry can’t attend the party _____ at Tom’s house at present because he is preparing the speech at the party _____ at Marie’s house tomorrow.选项:a、held/being held b、to be held/to be held c、 to be held/ held d、 being held/to be held

Henry can’t attend the party _____ at Tom’s house at present because he is preparing the speech at the party _____ at Marie’s house tomorrow.选项:a、held/being held b、to be held/to be held c、 to be held/ held d、 being held/to be held
Henry can’t attend the party _____ at Tom’s house at present because he is preparing the speech at the party _____ at Marie’s house tomorrow.
选项:a、held/being held b、to be held/to be held c、 to be held/ held
d、 being held/to be held
为什么选D?请分析并翻译整句

Henry can’t attend the party _____ at Tom’s house at present because he is preparing the speech at the party _____ at Marie’s house tomorrow.选项:a、held/being held b、to be held/to be held c、 to be held/ held d、 being held/to be held
Which is going (to be held) 即将举行的
或者是which is (being held) 正在举行的
括号前面的内容就是省略的部分.
例子一个：
I have a feeling that we are being followed.
我有种感觉我们正被人跟踪.

being held.从at present 看出，聚会正在进行
从tomorrow 看出明天要举办，to be held将来时

at present现在,所以用现在进行时被动语态
tomorrow明天,所以用不定式表将来时态
参考译文:亨利不能参加正在汤姆家中举行的聚会,因为他正在为明天玛丽家举行的聚会做准备