Since the Hawaiian Islands have never been connected to other landmasses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the ecology of the source area and that of the recipient area.
There is some dispute about the method of transport involved. Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport.
Did you ever have someone’s name on the tip of your tongue and yet you were unable to recall it (36) this happens again, do not (37) to recall it. Do something (38) for a couple of minutes, (39) the name may come into your head. The name is there, since you have met (40) person and learned his name. It (41) has to be dug out. The initial effort to recall (42) the mind for operation, but it is the subconscious (下意识) (43) that go to dig up a (44) memory. Forcing yourself to recall (45) never helps because it doesn’t (46) your memory; it only tightens it. Students find the preparatory method helpful (47) examinations. They read over the questions (48) trying to answer any of them. (49) they answer first the ones (50) which they are most confident. Meanwhile, deeper mental activities in the subconscious mind are taking (51) ; work is being done on the (52) <
A. then
B. really
C. only
D. indeed
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