若∠1和∠2互补,且∠1<∠2,则∠1的余角是( )
A:
B:
C:∠2—∠1
D:
1 13 57 24 90 15 2 68
①合数有____。
②质数有____。
③既是奇数又是合数的有____。
④既是质数又是偶数的有____。
—Is it allowed _______ your hair colorful in your school?
—No. Our teachers think it's bad for our health.
已知:3I2+6OH﹣═IO3﹣+5I﹣+3H2O
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