Generate a new sentence that follows the same structure of the sentence below.
The clouds were moving swiftly across the sky.
The cars were driving quickly down the highway.
Complete the following task based on the instruction and optional input provided.### Instruction:
Generate a new sentence that follows the same structure of the sentence below.

### Input:
The clouds were moving swiftly across the sky.

### Output:
The cars were driving quickly down the highway.