男性，62岁。反复右下腹疼痛，伴进行性消瘦半年，无腹泻。查体：贫血貌，右下腹可触及一

深度为5的满二叉树中，叶子结点的个数为______。

The next world war will be fought with stones。——Einstein（爱因斯坦）这种忧虑是源于科学家对某一次战争的反思。这次战争是指 [ ]

A、第一次世界大战

B、第二次世界大战

C、海湾战争

D、越南战争

Computers can injure you. Most other injuries happen suddenly. For example, if you fall off a bike and break your arms, it happens very quickly. But computer injuries happen slowly.

You probably know how to ride a bike safely. Now learn to use a computer safely.

Your eyes

Too much light can injure your eyes, so never sit too close to a computer screen. Your eyes should be at least 50cm from the screen. Remember to look away from it sometimes. This gives your eyes a rest.

When you use a computer, the window should be on your left or your right. If it is behind you, the light will reflect(反射) on the screen. If the window is in front of you, the sun and the screen will both shine into your eyes.

Your hands and wrists(手腕)

Hand and wrist injuries can happen because the hands and wrists are moved in the same way hundreds of times. If you use a keyboard for a long time, follow these rules: ①Rest your wrists on something. ②Keep your elbows at the same height as the keyboard. ③Stop sometimes and exercise your hands, wrists and fingers in a different way.

Your back

Some people sit for many hours in front of a computer. If you sit in the wrong way, you can injure your back or your neck. So you should sit with your back straight. The top part of the screen should be in front of your eyes. Your forearms, wrists, hands and the upper part of your legs should all the parallel (平行) to the floor. If you are sitting for a long time, get up every 30 minutes and exercise your arms, legs and neck.

小题1:A computer screen may injure your eyes if __________.

A. you sit 60cm away           

B. your eyes are too close to it

C. the window is on your left or right

小题2:Hand and wrist injuries are caused when you __________.

A. move in the same way again and again

B. rest your wrists on something

C. keep your elbows as high as the keyboard

小题3:When using a computer, your eyes and hands will be safe if you __________.

A. work near a window      

B. work for a long time    

C. take rests at times

小题4:It is good for your back and neck if you sit __________.

A. for many hours          

B. in the right way        

C. with the screen below your eyes

小题5:What would be the best title for the text?

A. How to Use a Computer Safely    

B. How to Keep your Hands and Wrists Safe

C. How to Protect your Eyes and your Back

下列补体活性片段中属于过敏毒素的是（）

A.C3a、C3b、C4a

B.C3a、C4a、C5a

C.C3b、C4b、C5b

D.C5a、C3b、C4b

E.C3a、C4a、C5b

乙级工程造价咨询单位的技术负责人要取得造价工程师证书，并具有工程或工程经济类高级专业技术职称，其从事工程造价专业工作应在( )年以上。

A．10

B．15

C．20

D．8