
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given that points $C$ and $D$ are two moving points on the ellipse $\frac{x^2}{4} + y^2 = 1$, and point $M(0, 2)$. If $\overrightarrow{MD} = \lambda \overrightarrow{MC}$, then the range of values for the real number $\lambda$ is _______.

Present the answer in LaTex format: \boxed{Your answer}
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