請依下文回答第 16 題至第 20 題 There are many amazing underground creatures. The stars of the underground show are earthworms,__16__ their role in building soil, their importance to gardeners, and the fascination they afford schoolchildren.
Earthworms are giants compared with most other soil__17__ . The earthworm’s body is made of__18__ cylinders, which look like many little rings joined together. They are__19__ that chew their way through
soil, feeding on plant and animal detritus and on microbes, digesting and thoroughly mixing organic and
inorganic components before eliminating it as humus. This__20__breaks complex organic molecules down
into simpler forms more suitable for uptake by plants.
【題組】20
(A) process
(B) shuttle
(C) liability
(D) hamper