下列有关3／4冠牙体预备的叙述，正确的是（） A.临床牙冠长，倒_爱下问搜题

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问题单项选择题

下列有关3／4冠牙体预备的叙述，正确的是（）

A.临床牙冠长，倒凹大者，邻面冠边缘应止于龈缘

B.上前牙切斜面由舌侧斜向唇侧

C.在切端斜面舌1／3处，做一顶角90°的沟

D.舌轴壁的侧凹不必消除，可以舌隆突为界分两段预备

E.邻沟与邻面的线角清晰，有棱角

答案

参考答案：B

解析：临床牙冠长，倒凹大时，冠边缘可在龈缘以上，冠覆盖区内应无倒凹，故A错误。上前牙切斜面由舌侧斜向唇侧，这样可以尽可能的少暴露金属，故B正确。切面沟制备时，先将倒锥钻或小倒锥钻放在切斜面的中间部位，形成"V"形沟。沟底应位于近舌侧的1／3处，故C也是错误的。舌轴壁的倒凹一定要磨除，以保证修复体就位、密合，故D错误。邻沟与邻面的线角应清晰而无明显棱角，棱角处修复体有应力集中易造成修复体折断，故E错误。只有答案B的描述是正确的。考点：3／4冠牙体预备要点

单项选择题

In a country that defines itself" by ideals, not by shared blood, who should be allowed to work and live here In the wake of the Sept. 11 attacks these questions have never seemed more pressing.
On Dec. 11, 2001, as part of the effort to increase homeland security, federal and local authorities in 14 states staged " Operation Safe Travel"—raids on airports to arrest employees with false identification. In Salt Lake City there were 69 arrests. But those captured were anything but terrorists, most of them illegal immigrants from Central or South American. Authorities said the undocumented worker’s illegal status made them open to blank mall by terrorists. Many immigrants in Salt Lake City were angered by the arrests and said they felt as if they were being treated like disposable goods. Mayor Anderson said those feelings were justified to a certain extent. "We’re saying we want you to work in these places. We’re going to look the other way in terms of what our laws are, and then when it’s convenient for us, or when we can try to make a point in terms of national security, especially after Sept. 11, then you’re disposable. There are whole families being uprooted for all of the wrong reasons. " Anderson said.
If Sept. 11 had never happened, the airport workers would not have been arrested and could have gone on quietly living in America, probably indefinitely. Ana Castro, a manager at a Ben & Jerry’s ice cream shop at the airport, had been working 10 years with the same false Social Security card when she was arrested in the December airport raid. Now she and her family are living under the threat of deportation. Castro’s case is currently waiting to be settled. While she awaits the outcome, the government has granted her permission to work here and she has returned to her job at Ben & Jerry’s.

What do we learn about And Castro from the last paragraph（）

A．She will be deported sooner or later.

B．She is allowed to stay permanently.

C．Her case has been dropped.

D．Her fate remains uncertain.

单项选择题 B型题

咽后脓肿最危险的并发症是（）

A.发热、拒食、声音改变

B.呛咳、呼吸困难

C.脓肿偏于一侧

D.脓肿破裂

E.X线检查