物体做匀速直线运动，则[ ]
A．物体的内能一定增大
B．一定只受一对平衡力的作用
C．物体所受合力一定为零
D．物体的机械能一定不变
答案：C
Encouraged by my science teacher, I set about my studies on developing my product, _____I hope I will succeed in applying for a patent（专利）.
A．with whom
B．to whom
C．through which
D．for which
下面化合物具有光学活性的是
A．大豆素
B．山奈酚
C．槲皮素
D．葛根素
E．儿茶素
