Why was it possible for these ancient trees let more light through than modern ones?
A.Because they were closely spaced, only 3 to 16 feet apart.
B.Because they were smaller plants and shrubs.
C.Because their branches did not fan out as far as to form. a shape like umbrella.
D.Because they had very small leaves like that of fern and dropped easily.
第7题
关于增感屏的结构,下列叙述错误的是
A.包括基层
B.包括保护层
C.包括乳剂层
D.包括荧光体层
E.包括反射层或吸收层
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