请教GWD-9-Q23

AlienX

hmm...actually, A is better than D in a sense that A expresses the relationship between "a new type of jet engine is being tested" and "that could eventually propel...".
The implied relationship is saying, "the test result of the new type of jet engine tell us that the new type of engine could eventually propel..."
Let's look at E:
A new type of jet engine is being tested, and it (the new type of jet engine) could eventually propel...
This structure tells us 2 unrelated things: the engine is tested, and the engine could eventually propel...
OG10 has at least one question testing the different between "that" and "and".  The explanation explicitly says that "and" constructs a sentence to discuss two unrelated "things".
I can't remember the exact question #.  If I find it, I will post under this thread.

cyyp

ha，我也选E

A里面这个that是没道理的。