No one________ in the classroom at that time. [ ]
A. was
B. is
C. were
D. are
答案:A
以下不属于斑氏丝虫微丝蚴形态特点的是()
A.体态弯曲自然
B.体核分布不均
C.头间隙长宽相等
D.无尾核
E.头端钝圆,尾尖细
生物灰岩在电性上的特征是()
A、低自然伽马,高电阻,低声波值。
B、低自然伽马,低电阻,高声波值。
C、低自然伽马,低电阻,低声波值。