离心泵的二级项修检修周期是累计运行（）h。A.2000 B.3000 C.4000
题型：单项选择题
问题：
离心泵的二级项修检修周期是累计运行（）h。
A.2000
B.3000
C.4000
D.2500
题型：单项选择题
根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
Richard’s father died when he was five. Later he lost his mother. An old woman felt sorry for the poor boy and often helped him. Of course he had no money to go to school. He had to 
work for a rich farmer. The man paid him nothing except food and clothes 小题1:. He found some old books near the school and taught himself to read and write.
小题2:.It connected the village and the town. One morning people found there was a big stone on it. It stopped them from going to town. They had to move it away, or they had to cross the mountain if they had something to do
in the town. But the stone weighed thirty tons at least and the strongest young men couldn’t do that. 小题3: Richard looked at it carefully for a while and said, “I have a way to move it away.” But few men believed him. 小题4: Night fell and people went home. Only the boy stayed there. To their surprise, the villagers found the stone was gone the next morning. They didn’t know
which spirit had moved it away小题5: .
“How could he?” the rich farmer called out, “ He’s only fifteen! He couldn’t move it at all.”
“He dug a big hole beside the stone” said the old woman, “And then he could easily push it into the hole!” Looking at each other, the farmer couldn’t say a word.
A．There seemed to be nothing strange in the village.
B．An old woman said Richard had done it all.
C．There was a narrow path between two mountains.
D．But the boy didn’t lose heart.E. Some farmer even laughed at the boy.
F. The boy hoped he could do something for the villagers some day.
They discussed for a long time, but nobody knew what to do.