当然，这种说法虽然形象，但并不严谨。
Certainly, this kind of parlance although image, not careful.
但是只凭相信并不严谨。
实际上，我们对二重积分的定义并不严谨，那应该怎样严格地定义它呢？
OK, so actually, how do we define it, that's not really much of a definition yet.
实际上，我们对二重积分的定义并不严谨，那应该怎样严格地定义它呢？
OK, so actually, how do we define it, that's not really much of a definition yet.
应用推荐