若要检查 * * 损伤的程度，应使用的器械是 A．金属探子 B．金属导管 C．普通导尿管

Why is (71) fun What delights may its practitioner expect as his reward First is the Sheer joy of making things．As the child delights in his mud pie，So the adult enjoys building things，especially things of hid own design．Second is the pleasure of making things that are useful to other people．Third is the fascination of fashioning complex puzzle-like Objects of interlocking moving parts and Watching them work in subtle cycles，playing out the consequences of principles built in from the beginning．Fourth is the joy of always learning， Which Springs from the (72) nature of the task．In one Way or another the problem id ever new, and its solver learns something：sometimes (73) ，sometimes theoretical，and sometimes both．Finally there is the delight of Working in such a tractable medium．The (74) ，like the poet，works only slightly removed from pure thought-stuff. Few media of creation are so flexible，so easy to polish and rework，so readily capable of realizing grand conceptual Structures． Yet the program (75) ，unlike the poet's words，is real in the sense that it moves and works，producing visible outputs separate from the construct itself．It prints results，draws pictures，produces sounds，moves arms．Programming then is fun because it gratifies creative longings built deep Within us and delights sensibilities we have in common With all men．

（74）处填（）。

A．poet

B．architect

C．doctor

D．programmer

均匀导线制成的单位正方形闭合线框abcd，每边长为L，总电阻为R，总质量为m。将其置于磁感强度为B的水平匀强磁场上方h处，如图所示。线框由静止自由下落，线框平面保持在竖直平面内，且cd边始终与水平的磁场边界平行。当cd边刚进入磁场时。

（1）求线框中产生的感应电动势大小；

（2）求cd两点间的电势差大小；

（3）若此时线框加速度恰好为零，求线框下落的高度h所应满足的条件。

按仪表的工作原理不同分（）（）（）（）。

下列情况①关小排出阀；②关小吸入阀；③油温升高；④油温降低；⑤发生因油现象；⑥发生“气穴’现象，会使齿轮油泵排压升高的是（）。

A.①③⑤

B.①④⑤⑥

C.①

D.①④

怎样安全排放导淋？