protoplanetary nebulae造句

例句与造句

1. Such features are also seen in Galactic carbon-rich protoplanetary nebulae.
2. Indeed, the cosmic synthesis of nanocrystalline diamond may be occurring today in so-called protoplanetary nebulae, a relatively brief stage in the evolution of red-giant stars, which our own sun will enter in the far distant future.
3. On the other hand, the X-like shape and the low velocity of the outflowing gas in the Red Rectangle are peculiar, probably because its origin ( associated to a stable, extended disk ) is different than for most protoplanetary nebulae.
4. It's difficult to find protoplanetary nebulae in a sentence. 用protoplanetary nebulae造句挺难的