下列事例应用了三角形稳定性的有（ ）
①人们通常会在栅栏门上斜着钉上一根木条； ②新植的树木，常用一些粗木与之成角度的支撑起来防止倒斜； ③四边形模具．
A：1个
B：2个
C：3个
D：0个
⑴What colour is her dress ?____ A、It's Mike's .
⑵What time is it now ?____ B、It's white and black .
⑶Whose is this ?____ C、They are apples .
⑷What are they ?____ D、No , she isn't .
⑸Is your mother at home ?____ E、It's five o'clock .
We saw some birds. beautiful.
