Present Simple
He can pick many apples off the tree
He is able to pick many apples off the tree
Past Simple
He could pick many apples off the tree
He was able to pick many apples off the tree
Future Simple
He ( can - не испольдуется в этом времени)...?
He will be able to pick many apples off the tree
Present Simple
He can pick many apples off the tree
He is able to pick many apples off the tree
Past Simple
He could pick many apples off the tree
He was able to pick many apples off the tree
Future Simple
He ( can - не испольдуется в этом времени)...?
He will be able to pick many apples off the tree