单项选择题
A.extinct
B.permanent
C.surplus
D.intrinsic
单项选择题 The kitchen was small and ()so that the disabled could reach everything without difficulty.
单项选择题 During the construction of skyscrapers, cranes are used to ()building materials to the upper floors.
单项选择题 The ties that bind us together in common activity are so ()that they can disappear at any moment.