a single ribosome的用法和样例：
- A single ribosome,especially one that is combined with a molecule of messenger RNA.
- A single ribosome, especially one that is combined with a molecule of messenger RNA.
- The letter was written on a single sheet of paper.
- He got over the stream with a single leap.
- In one extreme case, a single ribosomal protein gene known as RPL21 has spawned more than 140 pseudogene copies.
- The bridge crosses the river in a single span.