牙目前认为人类龋齿主要致龋菌是()
A．乳酸杆菌
B．唾液链球菌
C．血链球菌
D．变形链球菌
E．轻链球菌
参考答案：D
He realized she was crying ________ what he had said.
A．because
B．becauseof
C．as
D．since
物流成本只包括储存、装卸搬运所发生的费用。
