下图是叶片气孔的示意图，下列哪种物质不能由气孔进出叶片 [ ] A．氧气 B．二

男，42岁，右下肺炎，用青霉素治疗后热退，3天后又发热，白细胞总数持续增高。其原因首先考虑（）。

A.未用退热药

B.青霉素剂量不足

C.发生并发症

D.未用糖皮质激素

E.致病菌对青霉素耐药

属于强极性化合物的是：（）

A.叶绿素

B.氨基酸

C.季铵生物碱

D.高级脂肪酸

E.油脂

The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals, (31) this is largely because, (32) animals, we stand upright. This means that our noses are (33) to perceiving those smells which float through the air, (34) the majority of smells which stick to surfaces. In fact, (35) , we are extremely sensitive to smells, (36) we do not generally realize it. Our noses are capable of (37) human smells even when these are (38) to far below one part in one million.
Strangely, some people find that they can smell one type of flower but not another, (39) others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate (40) smell receptors in the nose. These receptors are the cells which sense smells and send (41) to the brain. However, it has been found that even people insensitive to a certain smell (42) can suddenly become sensitive to it when (43) to it often enough.
The explanation for insensitivity to smell seems to be that the brain finds it (44) to keep all smell receptors working all the time but can (45) new receptors if necessary. This may (46) explain why we are not usually sensitive to our own smells—we simply do not need to be. We are not (47) of the usual smell of our own house, but we (48) new smells when we visit someone else’s. The brain finds it best to keep smell receptors (49) for unfamiliar and emergency signals (50) the smell of smoke, which might indicate the danger of fire.

A．introduce

B．summon

C．trigger

D．create

公积金提取时，下列情形不属于销户提取的（）

A、退休

B、出境定居

C、死亡

D、偿还商业贷款的

柴油发动机必须有可靠的调速装置，使其在一定范围内稳定运转，这一装置即（）。

A.喷油器

B.调速器

C.输油器

D.调温器