(-0.7)2的平方根是( )
A.-0.7
B.±0.7
C.0.7
D.0.49
∵(-0.7)2=0.49,
又∵(±0.7)2=0.49,
∴0.49的平方根是±0.7.
故选B.
_____, Mother will wait for him to have dinner together. [ ]
A. However late he is
B. However he is late
C. However is he late
D. However late is he
何谓肺硅沉着病简述其病变特点、分期和并发症?