下列起重机械中，( )的结构特点是悬架长(服务范围大)、塔身高(增加升降高度)、设

某地15人接种某疫苗后，测得其抗体滴度从1：20到1：320不等，为求其平均滴度，最好选用（）。

A.众数

B.算术均数

C.几何均数

D.中位数

E.百分位数

Well, when the huge wave hit the boat, my safety belt broke and I was swept overboard. I don’t really understand how it happened, but it did. I heard someone yell out, but then my boat, Wild One, went off into the darkness and I was alone in a very rough sea. I then spent five and a half hours in the water. The place where it happened was, oh, about 50 kilometers from shore. It was likely that I wouldn’t see another day, but I always thought I’d overcome the difficulties. At first I was watching out for Wild One. The rest of the crew knew I was gone, so they were sure to come back and look for me. After a while, I saw the boat’s lights when it came looking for me. They were within about 300 meters of me, but the spotlight just missed me. The reason why they didn’t see me was because of the huge waves. You know, I started sailing when I was seven, and started ocean racing when I was about eighteen, but I’d never been overboard before. I believed I was going to survive, but it was very cold, and as the hours passed I started to get desperate——and frozen! It was around 5 am when I saw the lights of a tanker coming towards me. I figured it was probably my last chance. At first, I thought they were going to miss me, and then they made a slight turn and I yelled out “Help!” and they heard me. Then another yacht appeared. These guys were terrific. They gave me dry clothes, and then one jumped into the bunk and hung onto me. They covered us with as much dry clothing as they could, and the guy in with me stayed to transfer his body heat to me.

小题1:The author of the passage was alone in the sea NOT because ______.

A．the wind was too strong

B．the wave hit the boat

C．the safety belt was broken

D．his boat was in the darkness小题2:He was not saved by his crew because ______.

A．he didn’t yell out “Help!”

B．300 meters was long distance

C．he was not found

D．he didn’t see the spotlight小题3:It was inferred from the passage that ______.

A．he was swept overboard at about midnight

B．Wild One was the name of a crew member

C．he started ocean racing at about seven

D．he was too hopeless to take the last chance小题4: One of the guys who saved him jumped into the bunk in order to ______.

A．cover him with more dry clothes

B．warm him with his body heat

C．comfort him

D．congratulate him

电力机车速度超过（）km/h时禁止使用电气制动。

A.10

B.15

C.20

D.25

黄连中的抗菌成分是

A．小檗碱
B．麻黄碱
C．莨菪碱
D．吗啡
E．乌头碱