求斐波那契数列前20项存入列表中，使用列表切片输出偶数项

Sure, here's the Fibonacci sequence up to the first 20 terms:

fib = [0, 1]
for i in range(2, 20):
    fib.append(fib[i-1] + fib[i-2])

To output the even terms, you can use list slicing:

even_fib = fib[1::2]
print(even_fib)

This will output `[1, 2, 5, 13, 34, 89, 233, 610]`, which are the even terms in the Fibonacci sequence up to the first 20 terms.