锐性切开的特点是（）、速度快、切口平整，但手术中出血较多。
参考答案：组织损伤小
Although we had told them not to keep us waiting, they made no _________ to speed up deliveries.
A．trial
B．attempt
C．action
D．progress
采用（）和小的电流是立焊时的工艺参数。
A、碱性焊条
B、酸性焊条
C、小直径焊条
D、大直径焊条
