According to the passage, frogs are vulnerable in backyards because they are ______.
If 5 frogs catch 5 flies in 5 minutes, how many frogs are required to catch 50 flies in 50 minutes?
If 5 frogs catch 5 flies in 5 minutes, how many frogs are required to catch 50 flies in 50 minutes?
If 5 frogs catch 5 flies in 5 minutes, how many frogs are required to catch 50 flies in 50 minutes?