Critical pre-launch tests have been hampered by issues with propellant loading and a malfunctioning helium check valve.

关键的发射前测试因推进剂装载问题和氦止回阀故障而受阻。

Fireworks tend to fall back down into bodies of water, polluting them with propellants and colorant residue.

烟花往往会掉回水体中，并被推进剂和着色剂残留物污染。