A:a; 不填
B:不填; a
C:the; 不填
D:不填; the
读某河流①②③④四个位置的沉积物颗粒组成图,完成下题.
— How do you like the regulations of our school?
— The regulations are strict with the students and they require that students _______ at least 90% of the lectures.
关于x的方程mx-1=2x的解为正实数,则m的取值范围是( )