变浮力式液位计是根据（）随液位的变化而变化来进行液位测量的。A、浮子（浮球、浮标）的

在照明电路中，接入一盏灯，通过灯的电流0.4A，灯的电阻为______Ω，此时超过了灯的额定电流，若要使灯的电流减小为0.25A，应______联一个______Ω电阻．

顺次连接任意四边形的各边中点得到的四边形一定是[ ]

A．正方形

B．矩形

C．菱形

D．平行四边形

灌注琼脂印模的正确方法是（）

A.复制工作模前，应先将工作模烤干

B.将适宜温度的琼脂印模材料以缓慢小水流式的速度灌入，避免因琼脂印模材料的液面上升过快而致模型表面产生气泡直至印模材料从孔洞内满出为止

C.将适宜温度的琼脂印模材料快速注入型盒内，以防琼脂冷却

D.将适宜温度的琼脂对准衬垫蜡的部位以较快速度灌入并边灌边振荡

E.将适宜温度的琼脂以缓慢小水流式的速度灌大型盒，但不能将型盒灌满

Jee Hock and Meng Kim were very good friends. Jee Hock could not see. He was blind. Meng Kim could not walk. He was lame. They lived in a village near a forest. Everyone in the village was going to a rich man’s dinner on the other side of the forest. Jee Hock and Meng Kim were anxious to attend the dinner too.

Blind Jee Hock thought of a plan. He would carry Meng Kim. The lame man could tell him the way. Meng Kim said that the plan was a good one.

On the way through the forest, Meng Kim saw a tiger. He did not tell Jee Hock about it. Instead, he quietly asked Jee Hock to carry him to the nearest tree. Upon reaching an over banging branch, Meng kim quickly hauled himself up.

Then the tiger roared. Jee Hock at once knew a tiger was near. He lay down quietly. The tiger came to him and sniffed his body. The tiger’s whiskers touched Jee Hock’s nose. At once Jee Hock sneezed, “Ah choooooo!” The tiger was afraid and ran away.

Then Meng Kim came down from the tree. He asked Jee Hock about the tiger. Jee Hock said that the tiger had told him to choose his friends wisely.

45. Jee Hock and Meng Kim were good ______.

A. men          B. tigers         C. friends         D. brothers

46. They decided to go to ______.

A. a picnic       B. a dinner       C. a party         D. the cinema

47. When Meng Kim saw the tiger, he ______.

A. shouted loudly                 B. did not tell Jee Hock about it

C. quickly climbed up a tree         D. lay down quietly

48. Jee Hock knew the tiger was near. He ______.

A. went to sleep                  B. cried

C. sat down and waited             D. lay down quietly

49. Jee Hock sneezed because the tiger’s whiskers ______.

A. hurt him                     B. was very long

C. cut his nose                    D. touched his nose

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