A.
B.
C.
D.
[单选题]A.-(l-x)a/lB.-x·b/lC.(l-x)a/lD.x·b/l
[单选题]A.-(l-x)a/lB.-x·b/lC.(l-x)a/lD.x·b/l
[单选题]A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条件(1)和条件(2)单独都不充分,但条件(1)和条件(2)联合起来充
[单选题]A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条件(1)和条件(2)单独都不充分,但条件(1)和条件(2)联合起来充
[单选题]A.1800B.1600C.1500D.750
[单选题]A.剪力为零,弯矩不为零B.剪力不为零,弯矩为零C.剪力和弯矩均为零D.剪力和弯矩均不为零
[单选题]A.剪力为零,弯矩不为零B.剪力不为零,弯矩为零C.剪力和弯矩均为零D.剪力和弯矩均不为零