已知等边三角形的边长为2cm,则它的高为______cm.
根据等边三角形:三线合一,所以它的高为:22-12=3cm.
Did her father hear her English when he passed?[ ]
A. speak to
B. speaking
C. spoken
D. to speak
数控机床的数控装置通常由输入装置;运算器;输出装置和()组成。