原式=22+2-4×22-1=1.
You’ve been working all morning –I think you _____a rest.
A.charge
B.admit
C.bargain
D.deserve
MG2×375-W采煤机的电磁阀是()。
A.四阀全为三位四通阀
B.四阀为三位四通阀,两阀为两通阀
C.两调高阀为二位阀,牵引阀为三位阀
D.调高阀为三位阀