I find ____ necessary to learn about the customs of a country before you go there.
句意:我发现在去一个国家前,学习那个国家的风俗习惯很有必要。that那,那个，表远指;this这,这个，表近指;it它,指代上文提到的对象;one一件,代表与上文同一类但不同一的事物。根据句意可知此处应是固定句型:find + it + adj. + to do sth.,表示“发现做某事……”,其中it是形式宾语,动词不定式作真正的宾语。故选C。
I find ____ necessary to learn about the customs of a country before you go there.
—Much personal information is stolen when people buy things on the Internet.
—Terrible! _____ must be done to keep the Internet safety.
—Where would you like to go this Mid-Autumn Festival?
—I’d like to go ____.
—It’s sunny outside. Why not go out and have a look?
—There ____ is here. I just want to have a rest.
There is ___ juice in the fridge. I must go to the supermarket at once to buy some.
____ of my time is spent on learning. So I have made much progress in my study.
Most students are playing on the playground and there are still ____ students staying in the classroom．
My twin brothers promised my parents to give up playing computer games, but ____ of them made it.
—I don’t know how to do. Any good suggestions?
—Don’t always think of yourself, and you should also think of ____.
—Would you like to play basketball or football?
— ____ is OK. I am good at both of them, so it’s up to you.
