1.What's the plural form of "it?"

　　2.Which is not a preposition: in, under, across, where?

　　3.Find the mistake in the sentence: "I received a M.B.A."

　　4."You can trust him. He's as close as an oyster."What's the Chinese equivalent(意义相当的东西) to "as close as an oyster"?

　　5.Find the mistake in the sentence: "Julius Caesar was assassinated(暗杀) 44 B.C."

　　6. Which is the correct plural form of children: children's or childrens'?

　　7.Use a prefix to make a one-word synonym of "not important."

　　8.Correct this sentence: "He swims very good."

　　9.Order from largest to smallest: man, apple, fly, elephant

　　10.Give four things a dictionary can tell you about a word besides its spelling.