命题“若x2＋y2＝0，则x、y全为0”的逆否命题是( )
A：若x、y全为0，则x2＋y2≠0
B：若x、y不全为0，则x2＋y2＝0
C：若x、y全不为0，则x2＋y2≠0
D：若x、y不全为0，则x2＋y2≠0
—Dr. Jackson is not in his office at the moment.
—All right. I____ him later.
A. Let's go.
B. Are these your shoes?
C. Let's play football.
D. They are on your feet．
E. What are they?
A：It's warm today．____
B：Great!____
A：Where are my shoes?
B：____
A：No．they aren't．
A：Look!____
B：Oh．I'm sorry．
设a=30.5,b=log32,c=log0.53，则（ ）
