to sit up straight; to straighten one's posture; to straighten up
to straighten oneself; to straighten one's clothes and one's posture; to adopt a more serious attitude
to go to the bottom of an affair; to inquire into the origin
to sit up straight; to straighten one's posture; to straighten up
to go to the bottom of an affair; to inquire into the origin
to enquire of someone about something (inquire); to question; to interrogate; to grill (someone about a matter); to question in detail
to find out the truth; to ascertain; to clarify; to confirm; to verify