求助大佬们

[gh_love_wj]

for i in range(1,21):
link = wd.find_element_by_css_selector("td[colspan='2'][align='left'][valign='top'] table:nth-of-type(i) a")
link.click()
请问各位大佬这个代码哪里出错了，为什么不能用i
selenium.common.exceptions.InvalidSelectorException: Message: invalid selector: An invalid or illegal selector was specified
(Session info: chrome=90.0.4430.93)