肺动脉瓣关闭不全的概述

HIV主要侵犯下列哪类细胞亚群（）

A.抑制性T淋巴细胞

B.辅助性T淋巴细胞

C.B淋巴细胞

D.NK细胞

在背书转让汇票时未记载日期的，视为在()背书。

A．出票日

B．汇票到期日前

C．汇票提示承兑日之前

D．汇票提示付款日之前

LTE的切换控制方式是？（）

A.NCHO

B.NAHO

C.MCHO

D.MAHO

Last year the worldwide paper industry used over twice as much fresh pulp (pulp made directly from raw plant fibers) as recycled pulp (pulp made from wastepaper). A paper-industry analyst has projected that by 2010 the industry will use at least as much recycled pulp annually as it does fresh pulp, while using a greater quantity of fresh pulp than it did last year.
If the information above is correct and the analyst’s projections prove to be accurate, which of the following projections must also be accurate

A．In 2010 the paper industry will use at least twice as much recycled pulp as it did last years.

B．In 2010 the paper industry will use at least twice as much total pulp as it did last year.

C．In 2010 the paper industry will produce more paper from a given amount of pulp than it did last year.

D．As compared with last year, in 2010 the paper industry will make more paper that contains only recycled pulp.

E．(E) As compared with last year, in 2010 the paper industry will make less paper that contains only fresh pulp.

雷电过电压可分为直击雷电过电压和感应雷电过电压两种