单项选择题 The passage suggests which of the following about the increased resistance to harmful root fungi that some Plants infected with mycorrhizal fungi seem to exhibit

单项选择题 It can be inferred from the passage that which of the following has been a factor influencing the extent to which research on mycorrhizal fungi has progressed

单项选择题 The level of information in the passage above is suited to the needs of all of the following people except ______.