在GWD29-2中
...... is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth’s magnetic field
of用法为：studies of A and of B....
在GWD29-26中：
......results from the combined gravitational pull of the Sun and all the other planets, each contributing according to its mass and distance from the others.
这里of用法为：gravitational pull of A and B...
如果换成：gravitational pull of A and of B...可以吗？
以上这两种用法都可以吗？哪种更好呢？thanks!!!