挑战习题
1/5单选题
难度:

1.设集合A={1,2},B={2,3},则AB等于(  )
A {1,2,2,3}
B {2}
C{1,2,3}
D {1}
提示1:
IOaxgumbhuWQiOeahOW5tumbhu+8jOWwseaYr+aKiui/meS4pOS4qumbhuWQiOS4reeahOWFg+e0oOaUvuWcqOS4gOS4qumbhuWQiOS4re+8jOS9huaYr+imgeWBmuWIsOWFg+e0oOS4jemHjeWkje+8gQ==
正确答案:Qw==
6Kej5p6Q77ya5rGC6ZuG5ZCI55qE5bm26ZuG77yM5bCx5piv5oqK6L+Z5Lik5Liq6ZuG5ZCI5Lit55qE5YWD57Sg5pS+5Zyo5LiA5Liq6ZuG5ZCI5Lit77yM5L2G5piv6KaB5YGa5Yiw5YWD57Sg5LiN6YeN5aSN77yBPGk+QTwvaT7iiKo8aT5CPC9pPjxpPj08L2k+ezEsMiwzfTxicj7mlYXpgIlD