我国（）的出口企业，遭遇到国外的专利技术壁垒。A、80% B、15% C、60% D、50

电梯机房的噪声平均值应不大于（）dB（）。

A．55

B．65

C．80

D．85

患者男性，42岁。既往体健，2周前体检发现脾大，今日突然呕鲜血200ml，解柏油样大便350ml。

解除门静脉高压的主要方法是（）

A.反复内镜下注射硬化剂

B.内镜下高频电灼

C.反复内镜下食管曲张静脉套扎术

D.长期口服心得安

E.经颈静脉肝内门体分流术

F.三腔二囊管压迫止血

G.长期静脉滴注小剂量垂体素

农业生态系统能流分析的步骤。

You cannot see any object unless light from that object gets into your eyes. Some of the things you see give off light of their own. The sun, the stars, a lighted lamp are examples that can be ssen by their own light. Such things are luminous. Most of the things you see are not giving off light of their own. They are simply reflecting light that falls on them from the sun or some other luminous bodies. Then moon , for example , does not give off any light of its own. It is non-luminous. You see it because sunlight falls on it and some of it reflects in your direction. So moonlight is only secondhand sunlight.

When you look at a book, it sends your eyes some of the light that falls on it, and you see the book. If light could be kept out from where you are so that there would be no light for the book to reflect, then you could not see the book even with your eyes wide open.

Light travels so fast that the time in which it travels from the book you are reading to your eyes is so short as if it took no time at all. Light reaches us form the moon , which is about 380,000 kilometers away, in only a little more than a second.

小题1:You can see the book because___________.

A．your eyes are close to it .

B．it reflects light

C．it has light of its own

D．your eyes can get to it小题2:The word “ reflects”  means____________.

A．throws back

B．takes back

C．gives off

D．sends out小题3:    ___________ have light of their won.

A．the sun and the moon

B．The stars and the earth

C．The sun and the stars

D．The moon and the earth

商业银行采用高级内部评级法，有效期限为1年和内部估计的有效期限两者之间的较大值，但最大不超过5年，中小企业风险暴露的有效期限可以采用（）。

A.2年

B.3.5年

C.2.5年

D.3年