问题
选择题
—_____ do you visit your teacher who taught you years ago?
—Once a year.[ ]
A. How long
B. How soon
C. How often
D. How many
答案
答案：C
搜题请搜索小程序“爱下问搜题”
—_____ do you visit your teacher who taught you years ago?
—Once a year.[ ]
A. How long
B. How soon
C. How often
D. How many
答案：C
缺失，设计
作基牙，固定桥修复。固位体和桥架用金合金分段铸造，然后焊接起来，在焊接过程中固位体不慎被烧坏。下列哪项不是焊料焊接中烧坏焊件的原因（）