用显微镜观察用清水处理过的洋葱表皮细胞时,不易观察到的结构是[ ]
A.细胞壁
B.细胞膜
C.细胞核
D.液泡
答案:B
工业是采矿业、制造业以及电力、热力、燃气及水的生产和供应业三个国民经济行业门类的总称。()
—Thank you for your gift. You are so sweet.
—______.
A.Don’t mention it.
B.I’m glad you like it.
C.Please don’t say so.
D.No, it isn’t good.