reflexive pronouns 的疑問

I took an umbrella with myself.
I tried to study,but I couldn't concentrate.
Answer:-(of a verb) having a reflexive pronoun as its object as in to unbrella with myself=error,because the Object is "umbrella"
"I couldn't concentrate" is not the Object, but the Subject! "I".
eg:-I tried to study but couldn't concentrate on (myself). has been referring back to the subject of a sentence esp. of a pronoun,eg:-myself.
Try learn Grammar reflexive adj and n.
reflexively adv
reflexiveness n
reflexivity n

reflexive pronoun:

myself...通常用於作為object(受者)本身的意思

例如
I live by myself. [我是「自己一個人」住的]

因此個詞的意思和用法是要表達那個人(i/he/she/they)自身的狀態而不是個人的本體(角色或地位)

I took an umbrella.這句基本上已完整句...只是後面附加的「我」是強調我動作的主動性/有意識用意，with之後用普通pronoun=me就已經合理地表達相對umbrella這個object的took的動作跟我的關係是「我在」，而不是「我是」=myself.

I tried to study, but I couldn't concentrate.的I都是subject，而句子沒有或不需要reflexive pronoun是因為動詞(concentrate)本身是指我的情況。再用myself便會成為港式/中式英語-用了中文「我不能讓自己集中精神」等常見講法/思想/構思句子。當然英語仍是有用concentrate這類表示自己情況的動詞而會用reflexive pronoun作為加強「肉緊」情感的，寫/講法可以是：

I tried to study, but I just couldn't get myself to concentrate.
留意concentrate動詞由主動詞變為infinitive，動詞是「令我自己」做「集中精神」這動作。