I hear that Thailand is a good place to go sightseeing.

怎么课本上是I heard that Thailand is a good place to go sightseeing.而做题时课本上答案有成了hear

I hear that强调你现在听说 I heard that强调是你以前某个时间听说的。都对。

类似的例子有很多，随便想到两个
I am thinking you are a really good guy
I was thinking you are a really guy

I hear that he is coming.
I heard that he is coming.

如果只是一个句子，就填原形，一般现在时，表示一种普遍认可，如：the earth goes around the sun.

如果前后文是过去时态，就填heard

晕 2个都可以啊 只不过是时态的问题，这就好比，你今天可以吃饭，明天就不可以吃饭了？

我听说泰国是旅游观光的好地方 应该是heard