问题
选择题
______,the boy couldn’t enter his house.
A．Since the key had lost
B．T
he key being lost
C．Lost the key
D．Having lost the key
答案
Ｂ
独立主格结构作原因状语。
搜题请搜索小程序“爱下问搜题”
______,the boy couldn’t enter his house.
A．Since the key had lost
B．The key being lost
C．Lost the key
D．Having lost the key
Ｂ
独立主格结构作原因状语。
垂直的平面的方程为（）。