ex1：	  https://drive.google.com/file/d/1mPkHM0JYZnpl4w4DFzkKgFGX-LL27Mi0/view?usp=sharing

ex2&3： https://drive.google.com/file/d/1jYpp4V1T1iTtA-B1C9sQ-Gw1t11VNxes/view?usp=sharing

ex4：	  https://drive.google.com/file/d/1LlbqJ00XgW6WJ1z_6r07xMOsJptk0C05/view?usp=sharing

ex5：	  https://drive.google.com/file/d/1isCT6yARbP7igiAHvL-ATxzuYhm16BpG/view?usp=sharing

ex8：	  https://drive.google.com/file/d/1z5XXNGJZFd61Pds-ziLDvuED-KGJkdp5/view

ex9：	  https://drive.google.com/file/d/1LTJgwffxr6Cv9ZOsnQJlwV5JQptwrI3N/view?usp=sharing

ex10：	  https://drive.google.com/file/d/15nc_5jzKvyVVrVpr_XszVv3onSK7VpqT/view?usp=sharing

ex11：  https://drive.google.com/file/d/1SWq_aHnjA6RpWea1nABCzR2pRcxyEj26/view?usp=sharing

ex13：  https://drive.google.com/file/d/1ACSOlhm9sxAzfSnqSnCI6S-zuoAwNJQV/view?usp=sharing

ex14：  https://drive.google.com/file/d/1qFQpR8VO9xbObfmp3lrG1Lb1eORpUfDt/view?usp=sharing