51.   It will only take a few more years for earth to be able to sustain human life.

52.   Life cannot be sustained without adequate nourishment.

53.   Some scientists theorize that lakes and seas may have sustained martian life.

54.   The court had struggled with the issue of whether the surgery would amount to intentionally killing Mary, whose heart and lungs cannot sustain life.

55.   The most valuable insight is the complexity of interaction between proteins as they build and sustain cellular life.