全称命题“$\forall x\in R,x^2-x+\frac{1}{4}\ge 0$”的否定是 （   ）

下列各句中，没有语病的一句是（    ）

已知x为实数，|x+$\frac{1}{x}$|一定等于（　　）

      Mr Green is an Englishman. He teaches English well His English classes are very interesting. He likes us and we like him, too.
Mr Green has two children----Mike and Nancy. Mike is eight and his sister Nancy is five. Mike goes to school but Nancy doesn't. Mr Green likes to wear a T-shirt and a pair of jeans. Football is his favorite sport. After school we often have a basketball match. Sometimes Mr Green watches and joins us. He plays basketball just for us.