_______ myself as an example, I changed my major when I became a postgraduate.

空格处应填Take，通常不会用 Taking 或 To take。即：

Take myself as an example, I changed my major when I became a postgraduate.

这样用的 Take myself as an example 为插入语，类似于 Believe it or not 之类用法（英语不说：Believing it or not 或 To believe it or not）。

你可能认为这里填现在分词 Taking 也可以，因为这里的 taking 的逻辑主语刚好也是后面句子的主语（I），但这只是巧合，假若主语不一致呢？比如：

_______ myself as an example, English is too difficult for me.

这个句子也要填 Take，此时你就不会想到要填 Taking 了吧！

我们以 Believe it or not（信不信由你）为例（不管句子主语是什么，believe都没有变化）：

That’s normal, believe it or not. 那很正常，信不信由你。

Believe it or not, he asked me to marry him! 信不信由你，他向我求婚了！

We were, believe it or not, in love with each other. 信不信由你，我们在相爱。

Believe it or not, I don’t actually dislike him. 信不信由你，我其实并不讨厌他。

Believe it or not, English food can sometimes be quite good. 不管你相信不相信，英国的饭菜有时候也相当好。

Believe it or not, we were left waiting in the rain for two hours. 信不信由你，我们冒雨一直等了两个小时。

Believe it or not, all the passengers came through the plane crash alive. 每不信由你，所有的乘客在飞机失亊以后还都活着。

Believe it or not, I've just won 1000 pounds in a competition! 信不信由你，我刚在比赛中廉得了1000 英镑的奖金！