单项选择题
People can help solve the problem of pollution by （）
A．urging their governments to control litter and waste B．cutting down the use of oil and other oil products C．reducing unnecessary buying, over-consumption and careless disposal of wastes D．Making anti-pollution advertisements
单项选择题 Many people see pollution as only part of （）
单项选择题 What happened when the man let go the rope（）
单项选择题 Why did the man fasten the end of the rope before he climbed up the ladder（）
