Read the sentence. select the words that best complete the two blanks. though the road they took was long and they continued to plod listless, steadily arduous, wearily steep, facetiously cumbersome, quickly diffident, marvelously

Explanation:

The term cumbersome is defined as "large or heavy and therefore difficult to carry or use". This is fitting for the first blank as the context expects a negative adjective that expresses difficulty.

The term steadily refers to something firmly fixed, supported, or balanced. This is fitting for the second blank as it can be used to describe a manner of walking. In this case, a plod (heavy) can be done steadily, but not quickly.