下图是某生物的精子细胞,根据图中的染色体类型和数目,判断来自同一个次级精母细胞的是
A.①②
B.②④
C.③⑤
D.①④
答案:B
In order to detect rot in manila lines,you should().
A.feel the surface of the line for broken fibers
B.measure the reduction in circumference of the line
C.observe any mildew on the outer surface
D.open the strands and examine the inner fibers
一般情况下,接在电动机控制设备侧电容器的额定电流不应超过电动机励磁电流的()倍。
A.0.8;
B.1.0;
C.1.5;
D.0.9。