设两个相互独立的随机变量<img src="/lqwvjeImg/fc/fc024994843fa881a01e1ffe359e5d00.png"style="width:33px;height:29px;">与<img src="/lqwvjeImg/27/27329f3abcaa98eb927e7a4c4e7e1759.png"style="width:28px;height:29px;">分别服从正态分布<img src="/lqwvjeImg/4f/4fb04418771bdc94387cc03e89eb4492.png"style="width:85px;height:40px;">和<img src="/lqwvjeImg/5a/5acfa75bdbd996854f2456e2b8a2e3dd.png"style="width:82px;height:40px;">,则( )<br>·<img src="/lqwvjeImg/28/283ed8ab85085f9faaff68c97be56bb6.png"style="width:205px;height:72px;"><br>·<img src="/lqwvjeImg/43/43c02c041015bcf082d1371186ac2eef.png"style="width:205px;height:72px;"><br>·<img src="/lqwvjeImg/d0/d0e428990bd7230b863eacdac3de8167.png"style="width:205px;height:72px;"><br>·<img src="/lqwvjeImg/16/167b7290da526c085bc1812a03dca2cd.png"style="width:205px;height:72px;">