若$x,y\in R$且满足$x+3y=2$，则$3^x+{27}^y+1$的最小值是（    ）

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     Hi, I'm John.There are four seasons in a year. I like them all. In spring, it's warm. There are pretty flowers everywhere. I often go on a picnic with my parents. Summer is hot. I often go swimming in the pool. I like to wear my sunglasses. In fall, the weather is cool. I can help my grandpa pick apples. Winter is white. I can make a snowman. And I can go skating, too.

如图甲，一束太阳光照射到中间开有“△”形小孔竖直放置的黑色薄木板AB上，阳光透过小孔在竖直放置与AB平行的光屏MN上形成一个太阳的椭圆形像，现在在小孔处用一块与小孔一样形状和大小的“△”形竖直放置的小平面镜填满，小平面镜镜面向左，把太阳光反射到竖直放置与AB平行的光屏MꞌNꞌ上，MꞌNꞌ到AB的距离与MN到AB的距离相等，如图乙所示，则在光屏MꞌNꞌ上形成光斑的形状为（  ）