—Never mind. I _______________ here for only a few minutes.
A:came
B:have been
C:have come
下列物质分类正确的是( )
小麦的生长发育需要大量的水分,如图是小麦根尖的结构图,吸水的主要部位和生长最快的部位分别是( )
用二进制计算:
(1)101110(2)+1001101(2);
(2)1001001(2)﹣101110(2);
(3)1001001(2)×1001(2);
(4)1110101(2)÷1101(2);
(5)1001(2)×1110(2)÷10101(2).