—The similarities between social networks are striking.—That ________ come as no surprise，because they are all products of the Internet. 

No student______ go out of school for snacks during the break without the teacher’s permission.

---Do you know how this disabled man succeeded in running such a big company?--- I don’t know , but I think he __________ many difficulties.

---Listen! Is Kitty in the next room?  ---No, it ______ be Kitty. She has gone to Beijing.

—This pair of shoes ____ belong to Jack. He likes this kind very much.—It ____ be his. It’s too large for him.