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更多“As there is a lack for stock o…”相关的问题
A.short of
B.missing
C.lack in
D.charging
请根据以下内容回答 60～64 题
A．An organ of higher plants， usually subterranean and having several functions，including the absorption and conduction of water and dissolved minerals， food storage，and anchorage of the plant in the soil. It is distinguished from the stem by its structure，by the manner in which it is formed， and by the lack of such appendages as buds and leaves.
B．It grow horizontally， as a food-storing organ， beneath the surface of the ground， and enables a plant to reproduce itself.It has nodes， buds，and tiny leaves and does not die when cut； replanted， it yields new plant.
C．both A and B
D．neither A nor B
第 60 题 一种起运输作用的器官是（）
如果f(x)=
(a＞0且a≠1),证明:f(x)+f(y)=f(xy),f(x)-f(y)=
设F [f(t)]= F(ω)， 试证明:
1) f(t)为实值函数的充要条件是F(-ω)=
;
2) f(t)为虚值函数的充要条件是F(-ω)=-
.
求f[f(x)].
