作为英语学习者。开始时最好是写简单的句子。这样才比较容易掌握正确的语法。我用两个简单的句子来改写你第二句子。你可以看到它们是更容易理解, 语法明确。My favorite subject is English. It is because English is useful. Our English classes always have great fun.
because小写,且前面不用标点符号
语法应该没错