26.(Because) it is often dependent of the conditions (of) crystallization, the composition of the (minerals) in a rock can be important (in determining) the rock;s geologic history.
是不是of要改成in?
39.(During first) ten years of the Space Age, (which began) in 1957, (more than) 500 artificial satellites were rocketed (into orbit) around the Earth.
是不是要改为during the first? 但我总觉得into orbit要改为into the orbit.不知道各位怎么认为?
原题是26.(Because) it is often dependent (of) the conditions of crystallization, the composition of the (minerals) in a rock can be important (in determining) the rock;s geologic history.