麻烦大家了
1.The photoperiodic response of algae actually depends on the duration of darkness,__
A.the light is
B.and not on light
C.but is not on the light
D.is not on light
2.__no real boundary to the part of the ocean referred to as a "deep" because of changing water levels and movements in the sea floor.
A.It is
B.To be
C.Being
D.There is
第二个我也知道选D,可是我也说不清楚别的为什么错.比如A