#include<iostream> using namespace std; int main() { int a = 99; if (a < 10) { cout << "a小于10\n"; } else if (a < 20) { cout << "a大于10小于20\n"; } else if (a < 40) { cout << "a大于10小于40\n"; } else if (a < 90) { cout << "a大于10小于90\n"; }else cout<<"a大于90\n"; return 0;