使用耙装机时,遇难有大块岩石或耙受阻时,不可强行牵引耙斗,应将耙斗退回1~2m重新耙取,以防断绳或烧毁电动机。()
参考答案:对
根据首字母写出正确的单词形式.
1. Edward d_______ himself to scientific research after graduating from university.
2. Most of the Americans v_____ for Obama to be president.
3. The design of the product must be r______ to people’s needs.
4. The fire started in the middle of the night, so most of the people were t_____ in the burning building.
5. The thief used a false i_____ to take money from the bank.
原电池产生电流的本质原因是 [ ]
A.原电池中溶液能电离出自由移动的离子
B.有两根导线将两个活泼性不同的电极连接
C.电极上进行的氧化还原反应的生成物为电子
D.电极上进行的氧化还原反应中发生了电子的转移