pip install -r requirements.txt failed

[RhythmHellO]

Collecting scipy~=1.4.1 (from -r requirements.txt (line 5))
Using cached scipy-1.4.1.tar.gz (24.6 MB)
Installing build dependencies ... error
error: subprocess-exited-with-error
.......
File "/private/var/folders/pc/sbd6mtzs5g57c9z_vqdnj2z40000gn/T/pip-install-1gioli0t/numpy_e9ee180d7c8849eda824a6ce3f216369/numpy/distutils/command/build_src.py", line 142, in run
self.build_sources()
File "/private/var/folders/pc/sbd6mtzs5g57c9z_vqdnj2z40000gn/T/pip-install-1gioli0t/numpy_e9ee180d7c8849eda824a6ce3f216369/numpy/distutils/command/build_src.py", line 153, in build_sources
self.build_library_sources(*libname_info)
File "/private/var/folders/pc/sbd6mtzs5g57c9z_vqdnj2z40000gn/T/pip-install-1gioli0t/numpy_e9ee180d7c8849eda824a6ce3f216369/numpy/distutils/command/build_src.py", line 286, in build_library_sources
sources = self.generate_sources(sources, (lib_name, build_info))
File "/private/var/folders/pc/sbd6mtzs5g57c9z_vqdnj2z40000gn/T/pip-install-1gioli0t/numpy_e9ee180d7c8849eda824a6ce3f216369/numpy/distutils/command/build_src.py", line 369, in generate_sources
source = func(extension, build_dir)
File "numpy/core/setup.py", line 669, in get_mathlib_info
raise RuntimeError("Broken toolchain: cannot link a simple C program")
RuntimeError: Broken toolchain: cannot link a simple C program
[end of output]

    note: This error originates from a subprocess, and is likely not a problem with pip.
    ERROR: Failed building wheel for numpy

how to fix it? please help~