The rain made us late. It was…	It was the rain that made us late.	
She left him because he had an affair. It was…	It was because he had an affair that she left him.	
That woman took your bag, not me! It was…	It was that woman who took your bag, not me!	
He went to the doctor only when he felt pains in his chest. It was only… 	It was only when he felt pains in his chest that he went to the doctor.	
She agreed to marry him only when he bought her a diamond ring. It was only…	It was only when he bought her a diamond ring that she agreed to marry him.	
His constant boasting irritates me most. What irritates…	What irritates me most is his constant boasting	
I like the perks most in my job. What I like…	What I like most about my job is (are)* the perks.	
I can’t understand why the government bailed out the banks. What I can’t understand…	What I can’t understand is why the government bailed out the banks.	
I’d like to know how we’re going to finish this job by Friday. What I’d…	What I’d like to know is how we’re going to finish this job by Friday.	
You need to speak to Colin, not Andy. It’s…	It’s Colin you need to speak to, not Andy.	
I like his sense of humor most. What…	What I like most is his sense of humour.	
I won’t tolerate cruelty to animals. One thing I….	One thing I won’t tolerate is cruelty to animals.	
She gave me a refund only when I threatened to write to the newspapers. It was only…	It was only when I threatened to write to the newspapers that she gave me a refund.	
The Chinese invented gunpowder. It was…	It was the Chinese who invented gunpowder.	
The payment terms made me feel uneasy. What…	What made me feel uneasy was (were)* the payment terms.	
You are always complaining, not me! It’s…	It’s you who are always complaining, not me!	

*    A what-clause is usually singular. However, if the object is plural, the verb can be plural in an informal style.