Roger had just walked into his office and that was when he was told that his plan had finally been approvedWhich of the following can be instead of the underlined(划线的) part to make the sentence better

I’d ______ the operation unless it isabsolutely necessary

_is often the case with elder people, my grandmatalked about my new hairstyle for at least 30 minutes.

How many students are there in each group— Usually each group _______ six students in our class.

Mr. Li ______ to Mary carefully when I entered the classroom this morning. —He is very patient ______ he is young.