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

601. Too (much/many) or Enough (3692 candidates)
602. Verbs of involuntary perceptions ... (2278 candidates)
603. Infinitive, continued ! (1968 candidates)
604. Infinitive after verbs expressing will power ... (8487 candidates)
605. Not everyone has ... (2178 candidates)
606. What about suggesting ... (3996 candidates)
607. Difficulties of the Passive Form (16213 candidates)
608. 'Make someone do'/'Have something done': (a little further) (42694 candidates)
609. We'd still like to work on more tenses ...(2/2) (1738 candidates)
610. We want to work with tenses ...(1/2) (2395 candidates)
611. Two simultaneous actions in the past ... (12438 candidates)
612. Cause ? Aim? Not mixing the two concepts ... (22136 candidates)
613. Absence of obligation (25005 candidates)
614. To talk someone into / out of doing something ... (2430 candidates)
615. Difficulties in Reported Speech (15467 candidates)
616. Will and Would: a little further (7199 candidates)
617. Used to / to be used to (33913 candidates)
618. Present continuous (11910 candidates)
619. Past simple and continuous (8905 candidates)
620. Express future (11959 candidates)