双滚筒提升机调绳时两容器必须空载，调绳期间在特殊情况下可进行单钩提升。
参考答案：错
必需脂肪酸提供热能占总热能
A．1%～3% B．10%～12% C．12%～14% D．20%～30% E．55%～65%
看图，将下列句子补充完整。
l. They were then. Now they are .
2. She was fat then. Now she is .
3. She was short then. Now she is .
4. She was four then.Now she is .
