#### 1. tf.Session()不能用.eval()
```python
with tf.Session(graph=g) as sess:
    sess.run(op,feed_dict)

with tf.Interactive(graph=g) as sess:
    sess.run(op,feed_dict)
    op.eval(feed_dict)
```

#### 2. tf.SessionInteractive()只有一个产生交互活动.eval()，且是最近一个。但两者都可用sess.run同时产生多个活动
```python
g1=tf.Graph()
g2=tf.Graph()
with g1.as_default():
	a = tf.constant([1.0, 1.0])
	b = tf.constant([1.0, 1.0])
	result1 = a+b
with g2.as_default():
	a = tf.constant([2.0, 2.0])
	b = tf.constant([2.0, 2.0])
	result2 = a+b
sess1 = tf.InteractiveSession(graph=g1)
sess2 = tf.InteractiveSession(graph=g2)
out1 = result1.eval() # 错误
out1 = sess1.run(result1) #正确
out2 = result2.eval() # 正确
```