∵2x2+3≠0且对x∈R都有2x2+3>0
∴x∈R
故答案为:R
下列哪项不是痄腮腮肿的特点:
A.肿胀以耳垂为中心
B.肿胀区边界不清
C.肿胀区皮肤发红
D.触诊有弹性感
E.腮腺导管口红肿
It’s time that I my hair cut. It’s the fifth time that I to the barber’s shop.
A.had; have gone
B.have; have gone
C.have; went
D.had; go