話し中, 話中, はなしちゅう
May take 'no'
1. busy (phone)
2. in talks, discussion underway
これで30分もお話中です。
だ
copula, See である, See です, plain copula
1. be, is
Auxiliary verb, See た・1, た after certain verb forms; indicates past or completed action
2. did, (have) done
See た・2, indicates light imperative
3. please, do