不参与Ⅰ型超敏反应的细胞是（）
A.嗜碱性粒细胞
B.肥大细胞
C.浆细胞
D.中性粒细胞
E.嗜酸性粒细胞
参考答案：D
有负外部影响时，生产者的最优产量大于社会理想产量。( )
--- How was your weekend ? --- ___________________
A．I’d like to visit my uncle for this weekend.
B．It was good.
C．Did you have a nice weekend ?
D．I used to spend my weekend in the country
