The author suggests that, because there are no hiding places in the oceans, whales anddolphins
A、sleep only when they are very young
B、cannot afford to sleep very much
C、usually dream while awake
D、take turns to sleep
Henry Manley's company was in deep trouble.
A、True
B、False
C、Not Given
Task 221. In most cases of cloud-to-ground lightning, the ground'ssurface__________22. One form of lightning that is ball lightning. __________23. Cloud lightning looks like a ribbon when its lighting channel__________24. Although not fully understanding processes of lightning, man__________25. Lightening can__________A. occurs most infrequentlyB. is shifted sideways by strong windsC. strike twice or more in the same spotD. is equipped with a good knowledge of various forms oflightningE. is estimated at 20 million a yearF. is positively charged