Can I ignore a child's tears?

Yaya is very sensitive, as we all know. Ever since we sensed it while she was very young, we have been trying very hard to protect and respect her. But sometimes i am so frustrated by her so-frequent tears. Lately she will lose tear over anything trivial. She didn't complain much, all i saw was that she's wiping her tears off her face. If there's really nothing for me to guess about, i just can not stay calm, which i know, is not good for her. Like this morning, she woke up and asked for skirts. I gave her tights, skirts to put on. Then suddenly, i noticed she was sobbing. Asking why? No answer. But crying harder. I felt so annoyed and had to give her a time-out. Later she told me that she cried because she was still sleepy, and last night she cried because she was tired. And when she is not upset, she CLEARLY knows that she doesn't have to cry even when she is tired, she should have used her words to let people know. Anyway, later when we arrived for school, her eyes turned red right away once she found out that neither of her own teachers was in the classroom. The other teacher who was there tried very hard to help her settle down while i was leaving, but i heard she cried out loudly... What should i do? Not trying to inquire about the reasons whenever i saw her tears? You know, sometimes seeing her standing alone in a corner and wiping her eyes can be heart-breaking for me. But I am afraid that she will take this as the only way to get attention if I show that i care too much.

There are sometime when i saw some kids crying loudly at some public area. The parents just let them cry while holding their hands or even standing by. Yaya seldom threw any big tantrum, almost never at public places. But her little cry...