单项选择题
The author mentions all of the following as reasons why plankton could be considered a human food source EXCEPT that it is ________.
单项选择题 SATAN, a program designed by Dan Farmer, can be used ________.
单项选择题 The author suggests in the last paragraph that ________.
单项选择题 By saying "... owners of well over half of all World Wide Web sites have set up home without fit- ting locks to their doors" (Lines 3--4, Par
