tests by here4u with the online test builder (650 tests)

621. Forms of verbs (3092 candidates)
622. If clauses (5611 candidates)
623. Present simple or continuous (28733 candidates)
624. Present simple (11337 candidates)
625. Present continuous (8620 candidates)
626. Forms of verbs (7321 candidates)
627. V - ing or infinitive (5145 candidates)
628. Relative pronouns (2973 candidates)
629. Prepositions and particles (1642 candidates)
630. Conditional present and past (23764 candidates)
631. Rephrasing and modals (11519 candidates)
632. For - since - ago and tenses (5868 candidates)
633. Use of tenses in a text (14044 candidates)
634. Rephrasing of verbs (4058 candidates)
635. Some forms of verbs (1806 candidates)
636. Prepositions and particles (1520 candidates)
637. To do or To make (2395 candidates)
638. To do or Not to do (1617 candidates)
639. A few difficult words (3054 candidates)
640. Question tags (1297 candidates)