Help me underline and identify teh clauses in this paragraph

Although for the wrong reason, the Chicago Symphony Orchestra's Centennial concert was a memorable event. Three of its most famous music directors participated: Solti, Barenboim and Kubelik. Immediately before the concert, a celebration dinner was held for special donors. There were some 400 of these, each paying at least $500 for the privilege of attending. At an event like this, it is customary to give diners a small gift, so each person was presented with an attractive alarm clock, gift-wrapped. Why so of the clocks were put in their boxes with the alarm switched on is a mystery, but this was the case. It is appropriate to remind the reader that the dinner guests went straight on to the concert, armed with these ticking timebombs! During the first half there were a few problems, with only an occasional beep being heard. However, after the interval more and more alarms were going off, so the concert had to be temporarily stopped and an announcement was made. As the clocks were inside boxes and gift-wrapped, nobody in the audience had realized what the problem was. Once the laughter had laughter had died down, they were instructed to take their gift outside the lobby. The rest of the evening then proceeded without incident