A:covered
B:reached
C:played
D:lasted
Mr Green always weekends playing with children.
选出与你所听内容相符的图片( )
一架光学显微镜的镜盒里有4个镜头,甲、乙一端有螺纹,甲较长;丙、丁无螺纹,丙较长。若要在视野中看到较大的细胞,宜选用( )