柠檬酸钠抗凝血的原理是A．与血液中Ca2+结合，使之不能发挥作用 B．抑制凝血酶的形

一列横波在t时刻的波形如图所示，振幅为1 cm，已知质点M开始振动的时间比质点N迟0.1 s，两质点的平衡位置相距2 cm.此时刻质点N的运动方向如何？质点M从此时刻起经0.6 s相对平衡位置的位移多大？在0. 6 s时间内波向前传播的距离是多少？

男性，43岁，因急性脑出血入院，目前病人对任何刺激均无反应，呼吸不规则，大小便失禁，两侧瞳孔扩大，角膜反射消失，其意识状态是()。

A．嗜睡

B．意识模糊

C．昏睡

D．浅昏迷

E．深昏迷

当代大学生职业观的特征是什么？

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 the 60F 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 the 20F. 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

在项目的概念阶段，管理层表示希望每一个新产品的预期收益都要超过它的开发成本。这是（）的实例。

A.假设

B.约束条件

C.使用约束优化法来选择项目

D.技术要求