下列命题中,假命题的是( )
A:∃x0∈R,sinx0+3cosx0=2
B:∀x∈0,+∞),ex-x>0
C:∃x0∈0,+∞,lgx0=-1
D:∀x∈-∞,0,2x2-3x-2>0
Ms Jones needs one____(人)to help her do the work.
设z=1-i(i是虚数单位),则2z+z-=( )
99÷3=____ 36÷3=____ 240÷6=____ 630÷9=____