1.
going down / descending
2.
to go down / to descend
3.
they went down / they descended
17.
they were going / they used to go
19.
equal / alike / the same
25.
ship / vessel / spacecraft
26.
it seems / he/she seems
27.
walking around / strolling
28.
it remains / is left / is located
29.
it was remaining / it used to stay / was located
30.
he/she/it leaves / goes out
