* "I'm checking my email before I start work." (Simple present tense)
* "He was checking the oil in his car." (Past continuous tense)
* "Have you finished checking the inventory?" (Present perfect tense)
* "The cashier is checking the customer's ID." (Present progressive tense)
You can also use "checking" in a noun phrase:
* "The checking process takes about 15 minutes."
* "The bank offers free checking accounts."