问题 单项选择题

一侧下颌骨磨牙区、下颌角及升支部渐进膨大的肿块,按之有乒乓球感。X线片示透明囊性阴影,呈多房性,房室大小不一致,阴影边缘呈切迹状。最可能的诊断是()。

A.牙源性角化囊肿

B.成釉细胞瘤

C.牙源性黏液瘤

D.牙源性钙化囊肿

E.牙源性纤维瘤

答案

参考答案:B

单项选择题

Yellowstone Weather

Yellowstone National Park is at high altitude. Most of the park is above 7,500 feet (2,275 meters).

Yellowstone’s weather is unpredictable. In summer, it may be warm and sunny with temperatures in the high 70F. At night in any given month, the temperature may drop close to freezing. So it is best to come prepared for cold evenings and mornings, especially if you are camping or hiking. When you leave your campsite, please leave it prepared for possible thundershowers and wind.

A sunny warm day may become fiercely stormy with wind, rain, sleet and sometimes snow. Without enough clothing, an easy hike or boat trip can turn into a battle for survival.

Seasonal Weather Information

Spring

Cold and snow continue into May, although temperatures gradually climb Early in spring, daytime temperatures average in the 40F to 50F; by late May and June, they may reach the60F and 70F. Nighttime lows fall below freezing.

Summer

Daytime temperatures are usually in the 70F, occasionally reaching the 80F in the lower elevations (高度). Nights are cool, temperatures may drop in the 40F and 30F—sometimes even the 20F. June can be cool and rainy; July and August tend to be somewhat drier, although afternoon thundershowers are common.

Fall

Weather can be pleasant, although temperatures average 10-20 degrees lower than summer readings. Nighttime lows can fall into the teens and lower. Snowstorms increase in frequency as the weeks go by or towards the end of the fall season.

Winter

Temperatures often stay near zero throughout the day, occasionally reaching high in the20F. Subzero nighttime lows are common. Annual snowfall averages nearly 150 inches in most of the park. At higher places, 200-400 inches of snow have been recorded.

What does the underlined word "readings" refer to().

A.literary works

B.books

C.announcements

D.figures

单项选择题