Here you have some links to verbal tenses explanation and activities:
PRESENT SIMPLE
PRESENT CONTINUOUS
PRESENT SIMPLE VS. PRESENT CONTINUOUS
PAST SIMPLE
PAST CONTINUOUS
PAST SIMPLE VS. PAST CONTINUOUS
PRESENT PERFECT SIMPLE
PRESENT PERFECT CONTINUOUS
PRESENT PERFECT VS. PAST SIMPLE
PRESENT PERFECT SIMPLE VS. PRESENT PERFECT CONTINUOUS
PRESENT SIMPLE VS. PRESENT PERFECT CONTINUOUS
PAST PERFECT SIMPLE
PAST PERFECT CONTINUOUS
PAST SIMPLE VS. PAST PERFECT SIMPLE
PAST PERFECT SIMPLE VS.PAST PERFECT CONTINUOUS1
PAST PERFECT SIMPLE VS. PAST PERFECT CONTINUOUS 2
FUTURE SIMPLE: WILL-BE GOING TO
WILL VS. BE GOING TO
WILL VS BE GOING TO 2
FUTURE CONTINUOUS
FUTURE PERFECT
FUTURE MIX
DIFFERENT TENSES
