1.log7为底6 < log7为底7 = 1
log6为底7 > log6为底6 = 1
so log7为底6 < log6为底7
2.log3为底π > log3为底3 = 1
log2为底0.8 < log2为底2 = 1
so log3为底π > log2为底0.8