—Oh, I notice it. Thanks for telling me.
A:says; don't
B:writes; don't
C:says; didn't
D:writes; didn't
在生物实验课上,小明想详细地观察洋葱表皮细胞结构,请你为他选择一种合适的观察仪器( )
保护水资源,人人有责.我国是缺水国家,目前可利用淡水资源总量仅约为899000亿m3,数据899000用科学记数法表示为( )