一艘科学考察船从A点(20°N,20°E)出发,到达与A点纬度相同,经线正好相对的B点,则B点的经度是( )
A:160°W
B:20°E
C:160°S
D:20°N
排序。
A. There are five books on the table.
B. It's small, but it's clean.
C. There is a doll on the bed.
D. Look! This is my room.
E. I like my room.
F. There is a table and a bed in my room.
____
写出下列各单项式的系数和次数:
30a
-x3
y
ab2c3
-3xy34
πr2
系数
次数
下列各运算中,正确的是( )