If
you can speak English conversationally, you will do well on the TOEFL iBT.
True? No.
There
is no connection between being a proficient English conversationalist and a
high TOEFL iBT score. I have known many test-takers who were fluent
conversationalists yet struggled with TOEFL. Why? Because when you speak
English conversationally, you are safe within your active vocabulary (see active vocab). TOEFL, however, tests your
passive vocab and your ability to analyze (reading and listening) and deliver
arguments (speaking and writing) by contextualizing under a time pressure.
That
said, being a proficient conversationalist is definitely a plus. If you are,
make sure you understand argument development.
