He has two sons,__________ work as chemists.

He has two sons,both of whom work as chemists.
这里的as做什么成分?

He has two sons ___work as chemists.
A.two of whom
B.both of whom
C.both of which
D.all of whom
请问为什么?D为什么错?有什么固定搭配吗?
红P135／123

____ different ages as the two chemists are,they are _______ the same interest.
A.Of,of B.At,/ C.Of,with D.At,in
为什么 麻烦讲详细些
四、be of+(表示种类、颜色、年龄、形状、价格等）名词，多用来表示主语的特征。这类结构的主语可以是人，也可以是物，其中的of可以省略。常用于该结构的名词有：kind,age,colour,size,height,shape,type,way,price等。如：
Several of the stamps were of the unusual kind.其中几张邮票是不同种类的。
The two boys are of the same age.这两个男孩年龄相同。
She is of a different way of thinking.她的思维方式与众不同。
These two kinds of article are of the same price.这两种物品价格相同。

Chemists have been studying why people cry.They say the body produces two kinds of tears.One kind
翻译

Chemists are usually the best people to read the dorctor's notes.But sometimes the doctors write so badly that even chemists can't make out what was written.
One day a lady wrote to a doctor,inviting him to have dinner with her family.A few days later she got a reply,but he wrote so carelessly that she coulan't read it.Her husband couldn't read the letter,either.
"What shall I do?"she said toher husband."How can we know if he is coming?And it's not polite to call the doctor and tell him that I can not read his writing."
Her husband thought hard and then he got a good idea.
"Take it to the chemist,"he said,"and he will be able to read it easily."
"That's great,"shouted the lady.
So she went to the chemist's shop.The chemist looked at the note carefully.
"Wait a moment,please,"he said politely,and went to the back of the shop.After ten minutes he returned with a large of bottle in hand.He gave the bottle to the lady and said,"Take one spoonful before every meal."
之后还会给追分得