数学形态学的基本运算有哪四种？
参考答案：
数学形态学的基本运算有四种：腐蚀、膨胀、开启和闭合
She ______ the national table tennis team in 1988. [ ]
A. joins
B. joined
C. took part in
D. took part
呕吐伴眩晕、眼球震颤可见于
A．脑栓塞B．脑震荡C．颅内血肿D．前庭器官疾病E．脑出血
