【单选题】No sooner _____ the boy fall into the pond than he ____ to his feet and went to the rescue.
C.
has he seen… is jumped
D.
did he see… had jumped
【单选题】There are studies indicating female with four different photopigments in a certain kind of cells have better color sensitivity than those with three different photopigments. What type of cell has the ...
C.
The Retina horizontal cell
D.
The photosensitive Retinal Ganglion Cells (pRGC)
【判断题】Each eye has approximately six million retinal cone cells. They are packed much more tightly in the center of our visual field a small region called the fovea than they are at the edges of the retina.
【单选题】Hardly ______ he entered the classroom when the rain began to fall in big drops.
【简答题】He’s working hard for fear that he__________. A.should fall behind B.fell behind C.may fall behind D.would fall behind