(2) sees, knows, is, plunges;
(3) perceived, thought, was, jumped;
(4) perceives, thinks, is, jumps;
(5) noticed, concluded, was, dived;
(6) notices, concludes, is, dives.
He —— in the water a white object, which he —— — the boy's dress. Then he —— into the roaring rapids.
When the first, third, and fifth sets of words are used, the action is represented as something that is past; but when the second, fourth, and sixth sets are used, the action is represented as going on at the present time.
The forms of verbs (action-words) which are given in the first, third, and fifth sets are used to indicate past time, and are called past tenses; and the forms given in the second, fourth, and sixth sets are used to indicate present time, and are called present tenses.