A lot of native English speakers these days no longer distinguish between asking permission (May I?) and stating ability (Can I?). You'll often hear kids say, "Mom, can I go out and play?" when they mean, "Mom, may I go out and play?" Sarcastic mothers are known to reply, "I don't know, can you?

In Japanese, it's easy to keep these two concepts apart. Asking permission is: Vte + mo + ii desu ka. こちらは座ってもいいですか。("May I sit here?" Literally, "Sitting here, is it good?") In casual conversation, I'd probably say, "Is it okay if I sit here."

Practice

• 今テレビを見てもいい？ Is it okay if I watch TV now?
• クレジットカードを使ってもいいでしょうか。May I use a credit card (to pay)?
• ここに車を止まってもいいですか。May I park (the car) here?
• 新しいくつを買ってもいいですか。May I buy new shoes?
• このワインを飲んでもかまいませんか。Do you mind if I drink this wine? You don't mind if I drink this wine, do you?

In addition to 「Vて＋も＋いい？」、「Vて＋も＋いいですか。」、and 「Vて＋も＋いいでしょうか。」 you can use 「Vて＋も＋かまいませんか」(you don't mind if, you don't care if, it doesn't matter if?). Or you can increase the politeness level of your request with 「Vて＋も＋よろしいですか。」