肝生成乙酰乙酸的直接前体是A．乙酰乙酰辅酶A B．HMG—CoA C．β-羟丁酸 D
题型：单项选择题
问题：
肝生成乙酰乙酸的直接前体是
A．乙酰乙酰辅酶A
B．HMG—CoA
C．β-羟丁酸
D．甲羟戊酸
E．β-羟丁酰辅酶A
题型：单项选择题
We always regard dogs as man’s best friends. But what about cats?
Cats can also do us a favor sometimes.
Here is a comparison of the two animals.
A Friend Helps You When You’re Sick.
| Dogs | When Catherine lay down on the sofa, Pepe stared(盯) into her eyes and kept sniffing(嗅). After being pushed away, he suddenly jumped onto her chest. That’s when Catherine felt a pain that made her visit a doctor, and a fast-growing cancer was found. Months later, however, Pepe started staring and sniffing again. It seemed strange, but sure enough, Catherine’s cancer had spread. |
| Cats | Alana immediately finds a chair when Tee sits and stares directly into her face. That’s because Tee is warning her that she is about to faint(昏倒), which can happen as often as three times a day. But Alana won’t get hurt if she sits down. Not only does Tee warn Alana, but also her husband. Then the cat stays with Alana until she recovers. |
| Dogs | Ryan fell into the water by accident. The river was full of ice, and Ryan was very cold and his body temperature was dropping dangerously low. Luckily, he was found by Chelsea, who was playing with her dog, Zion. “Zion knew the boy was in trouble,” says Chelsea. “Ryan grabbed onto the dog’s collar, and Zion just turned around and came back to the bank.” |
| Cats | Bernice says: “I was sleeping in my bedroom, and then I was woken by Joey screaming and running”. Then she found smoke around her. With Joey helping her, she managed to get out of the door. “I found him in a mailbox when he was young and now I feel very lucky. Without him, I’d have probably died in the smoke.” |
A．stare at her and keep sniffing
B．jump onto her chest suddenly
C．sit and stare directly into her face
D．scream and run小题2:What can we learn about Ryan?
A．He likes swimming in rivers.
B．He has a lovely dog, Zion.
C．Chelsea helped him swim back to the bank.
D．He was in danger when he was found by Chelsea.小题3:What happened when Bernice was sleeping?
A．She was badly hurt in a big fire.
B．She found the brave cat in a mailbox.
C．A fire broke out when she was sleeping.
D．She ran out of the burning house with the help of firemen.