建设项目总投资的计价依据，一般有( )。A．工、料、机价格依据 B．设备价格依据

将10 g CO₂和O₂的混合气体，通过装有足量过氧化钠的干燥管，反应后干燥管的总质量增加了5.6 g,则原混合气体中CO₂的质量分数为（   ）

A．32%

B．44%

C．56%

D．88%

Our boat floated on between walls of forest. It was too thick for us to get a view of the land we were passing through, though we knew from the map that our river must be passing through chains of hills from time to time. Nowhere did we find a place where we could have landed: although the jungle did not actually spread right down into the river, banks of soft mud prevented us from going ashore. In any case, what would we have gained by landing? The country was full of snakes and other dangerous creatures and the jungle was so thick that one would be able to advance slowly, cutting one's way with knives the whole way. So we stayed in the boat, hoping that when we reached the sea, a friendly fisherman would pick us up and take us to civilization.

As for water, there was a choice. We could drink the muddy river water, or die of thirst. We drank the water. Men who have just escaped from what appeared to be certain death lost all worries about such small things as diseases caused by dirty water. In fact, none of us suffered from any illness as a result.

One day we passed another village, but fortunately nobody saw us. We did not wish to risk being taken prisoners a second time: we might not be so lucky as to escape in a stolen boat again.

小题1: TOC \o "1-3" \h \z What they could see on the boat was only.

A．high walls

B．chains of hills

C．heavy woods

D．vast land小题2:They couldn't land because.

A．the mud on the shore was too soft

B．they could not find anyone

C．they could not find the mark on the map

D．the forest was too thick to go through小题3:From the passage, we can learn that.

A．they were in an uninhabited area

B．they were on a journey home happily

C．the country was a civilized society

D．the country was a tropical jungle coutry小题4:The best title for this passage might he______

A．I he Problem of Landing

B．Escape in the Jungle

C．An Entirely New Experience

D．Exploration of a River

青少年成年期疾病的早期预防有效的措施是（）

A.健康教育

B.合理膳食

C.适量运动

D.疾病监测

E.采用以上综合措施

霉变多发生在（）原料中。

A.粮食

B.畜肉

C.水产品

D.蔬菜

在大功率的发动机上由于热负荷大必须安装（）。

A、机油泵

B、过滤器

C、汽油泵

D、散热器