The diet is based on the premise that grapefruit has an enzyme that burns fat, says Andrea N. Giancoli, a spokesperson for the American Dietetic Association, but that enzyme has never been pinpointed.

美国饮食协会的发言人Andrea n . Giancoli说，这种饮食是以葡萄柚含有能燃烧脂肪的酶为前提的，但这种酶从未被准确地找出。

youdao

The U.N. mission's role in Syria was based on the premise that there would be a cessation to the violence, and failing that, "a calibration of effort in response to the situation on the ground would be appropriate, " Ban writes.

CNN: U.N. head outlines options for Syria mission