问题补充：
说一下原因,谢谢
Our city_will become/ is becoming /becomes_（become)more and more beautiful.
三种都行.前两种为好,第二种最好.
is becoming 我们的城市正变得越来越漂亮.
will become我们的城市会变得越来越漂亮的.
becomes我们的城市会变得越来越漂亮了.
意思有些微差别.
注意体会.