II. Rewrite these sentences by using "because" to replace "because of".
1) He couldn't meet you because of his business.
=>  He couldn't meet you because he had business.
2) Nobody can do this test because of its difficulty.
=>  Nobody can do this test because it is  difficult
IV. Combine these sentences into one. Use the word in brackets.
1) Minh didn't work hard. He failed in the final exam.(therefore)
=> Minh didn't work hard. Therefore, he failed in the final exam.
2) She was very unhappy. Her result was very bad. (because of)
=> ) She was very unhappy because of  her bad result