如果数轴上的点M表示﹣1,将M向左移动2个单位长度,再向右移动7个单位长度,最后M表示的数是( ).
4
They considered ______ a computer, which was considered ________ a great help in their work.
A.to buy; to be
B.buying; being
C.to buy; being
D.buying; to be
分层喷射混凝土时,后一层喷射应在前一层混凝土终凝后进行,一次喷射的最大厚度:拱部不得超过,边墙不得超过()
A.10cm,10cm
B.15cm,15cm
C.10cm,15cm
D.15cm,10cm