Do you know 5 year Treasure Bill from the US has the yield of less than 1%? Yes, they are really cheap.
Do you know the equivalent from China has the yield of about 6%!
So, borrow money at the interest rate of the US 5-year T-bills; use the proceeds to by the equivalent in China; and pocket the differences in interest rate. Cash will just rolling in. No risk.
This is why QE is not working.