下列可能为鼻和鼻窦炎症引起的疾病有（）。 A.喉炎 B.气管炎和支气管炎 C.咽和扁

算术表达式中，算术运算符的优先级次序为( )。

A．++，--，*，/，%，+，-

B．+，--，++，--，*，/，%

C．++，--，+，-，*，/，%

D．+，-，*，/，++，-，%

Because math is very interesting for him, _____ he likes it very much.

A. and B. so C. / D. for

下列各项应用的主要原理表达正确的是 （　　）

A．盐酸除铁锈：Fe₂O₃+4HCl=2FeCl₂+2H₂O

B．天然气做气体燃料：CH₄+O₂=CO₂+2H₂O

C．除去氧化铜中少量碱式碳酸铜：Cu₂（OH）₂CO₃

高温  .

 2CuO+CO₂↑+H₂O

D．服用Al（OH）₃治疗胃酸过多：2Al（OH）₃+3H₂SO₄=Al₂（SO₄）₃+6H₂O

A

Once there was a piano player in a bar (酒吧). People came just to hear him play. But one night, a lady asked him to sing a song.
"I don’t sing, "said the man.
But the lady told the waiter, "I’m tired of listening to the piano. I want the player to sing!"
The waiter shouted across the room, "Hey, friend! If you want to get paid, sing a song!"
So he did. He had never sung in public before. Now he was singing for the very first time! Nobody had ever heard the song Mona losa sung so beautifully!
He had talent(天赋) he was sitting on! He may have lived the rest of his life as a no-name piano player in a no-name bar. But once he found, by accident, that he could sing well, he went on working hard and became one of the best-known singers in the US. His name was Nat King Cole.
You, too, have skills and abilities. You may not fell that your talent is great, but it may be better than you think. With hard work, most skills can be improved. Besides, you may have no success at all if you just sit on your talent.

Which could be the best title(标题)for the passage ( )

A．Sing in the Bar

B．Achieve Success in Life

C．Never Lose Heart

D．Find Your Hidden Talent

牛仔面料原料成分可分为（）两类。