正四面体ABCD的外接球的球心为0,E是BC的中点，则直线OE与平面BCD所成角
题型：填空题
问题：
正四面体ABCD的外接球的球心为0,E是BC的中点，则直线OE与平面BCD所成角的正切值为 .
题型：填空题
阅读理解
Every
one has his own way of saying things and his own special expressions. Many American
everyday expressions are from colors.
Red is a hot color. Americans often use it to express "heat". They may say they are red hot about
something unfair. When they're red hot they are very angry about something. Fast loud music is popular
with many people. They may say the music is red hot.
Pink is a lighter kind of red. People sometimes say they're in the pink when they're in good health.
The expression was first used in America at the beginning of the 20th century. It probably came from
many babies who were born with a nice pink color showing good health.
Blue is a cool color. The traditional blues music in the USA is the opposite of(与……相反) red
hot music. Blues is slow and sad.
The color green is natural for trees and grass. But it's an unnatural color for humans. A person who
has a sick feeling stomach may say he feels a little green. A passenger on a boat who is feeling very sick
from high waves may look very green.
1. What does the expression "be red hot about" mean?
A. Be very angry.
B. Be unfair.
C. Be happy.
D. Be very popular.
2. Why do Americans use the color pink to express the meaning of healthy?
A. Because the color pink is lighter than the color red.
B. Because their ancestors(祖先) did so many years ago.
C. Because many healthy babies were born with the pink color.
D. Because it's a traditional expression.
3. What's the opposite of the red hot music?
A. Fast music.
B. Loud music.
C. Blues music.
D. Country music.
4. How many colors are mentioned in the passage?
A. 3.
B. 4.
C. 5.
D. 6.
5. Which is the BEST title for the passage?
A. Different Colors
B. Strange Expressions
C. Colorful World
D. Feelings Behind Color Words