Accounting own wds

1.Why do companies report trade receivables net of allowances of doubtful accounts?

2.What is a subsidiary?

3.What does the cash conversion cycle measure?

4.Arizona Tool Works lists trademarks and brands under both amortizable intangible assets and indefinite-lived intangible assets. What is the difference between these two categories? That is, how are these two categories reported differently in the financial statements?